gem error at 2.7/stable on CentOS

When I install 2.7/stable with snap on CentOS 7 and 8, I get the following error in gem. bundle, irb, rake, rdoc and ri also get the same error.

$ gem -v
/snap/ruby/181/lib/ruby/2.7.0/rubygems.rb:12: warning: already initialized constant Gem::VERSION
/var/lib/snapd/snap/ruby/181/lib/ruby/2.7.0/rubygems.rb:12: warning: previous definition of VERSION was here
/snap/ruby/181/lib/ruby/2.7.0/rubygems/compatibility.rb:15: warning: already initialized constant Gem::RubyGemsVersion
/var/lib/snapd/snap/ruby/181/lib/ruby/2.7.0/rubygems/compatibility.rb:15: warning: previous definition of RubyGemsVersion was here
/snap/ruby/181/lib/ruby/2.7.0/rubygems/compatibility.rb:18: warning: already initialized constant Gem::RbConfigPriorities
/var/lib/snapd/snap/ruby/181/lib/ruby/2.7.0/rubygems/compatibility.rb:18: warning: previous definition of RbConfigPriorities was here
/snap/ruby/181/lib/ruby/2.7.0/rubygems/compatibility.rb:27: warning: constant Gem::ConfigMap is deprecated
/snap/ruby/181/lib/ruby/2.7.0/rubygems/compatibility.rb:36: warning: constant Gem::ConfigMap is deprecated
/snap/ruby/181/lib/ruby/2.7.0/rubygems/defaults.rb:3: warning: already initialized constant Gem::DEFAULT_HOST
/var/lib/snapd/snap/ruby/181/lib/ruby/2.7.0/rubygems/defaults.rb:3: warning: previous definition of DEFAULT_HOST was here
/snap/ruby/181/lib/ruby/2.7.0/rubygems.rb:116: warning: already initialized constant Gem::RUBYGEMS_DIR
/var/lib/snapd/snap/ruby/181/lib/ruby/2.7.0/rubygems.rb:116: warning: previous definition of RUBYGEMS_DIR was here
/snap/ruby/181/lib/ruby/2.7.0/rubygems.rb:121: warning: already initialized constant Gem::UNTAINT
/var/lib/snapd/snap/ruby/181/lib/ruby/2.7.0/rubygems.rb:121: warning: previous definition of UNTAINT was here
/snap/ruby/181/lib/ruby/2.7.0/rubygems.rb:126: warning: already initialized constant Gem::WIN_PATTERNS
/var/lib/snapd/snap/ruby/181/lib/ruby/2.7.0/rubygems.rb:126: warning: previous definition of WIN_PATTERNS was here
/snap/ruby/181/lib/ruby/2.7.0/rubygems.rb:135: warning: already initialized constant Gem::GEM_DEP_FILES
/var/lib/snapd/snap/ruby/181/lib/ruby/2.7.0/rubygems.rb:135: warning: previous definition of GEM_DEP_FILES was here
/snap/ruby/181/lib/ruby/2.7.0/rubygems.rb:145: warning: already initialized constant Gem::REPOSITORY_SUBDIRECTORIES
/var/lib/snapd/snap/ruby/181/lib/ruby/2.7.0/rubygems.rb:145: warning: previous definition of REPOSITORY_SUBDIRECTORIES was here
/snap/ruby/181/lib/ruby/2.7.0/rubygems.rb:157: warning: already initialized constant Gem::REPOSITORY_DEFAULT_GEM_SUBDIRECTORIES
/var/lib/snapd/snap/ruby/181/lib/ruby/2.7.0/rubygems.rb:157: warning: previous definition of REPOSITORY_DEFAULT_GEM_SUBDIRECTORIES was here
/snap/ruby/181/lib/ruby/2.7.0/rubygems.rb:165: warning: already initialized constant Gem::READ_BINARY_ERRORS
/var/lib/snapd/snap/ruby/181/lib/ruby/2.7.0/rubygems.rb:165: warning: previous definition of READ_BINARY_ERRORS was here
/snap/ruby/181/lib/ruby/2.7.0/rubygems.rb:170: warning: already initialized constant Gem::WRITE_BINARY_ERRORS
/var/lib/snapd/snap/ruby/181/lib/ruby/2.7.0/rubygems.rb:170: warning: previous definition of WRITE_BINARY_ERRORS was here
/snap/ruby/181/lib/ruby/2.7.0/rubygems.rb:177: warning: already initialized constant Gem::LOADED_SPECS_MUTEX
/var/lib/snapd/snap/ruby/181/lib/ruby/2.7.0/rubygems.rb:177: warning: previous definition of LOADED_SPECS_MUTEX was here
/snap/ruby/181/lib/ruby/2.7.0/rubygems.rb:1367: warning: already initialized constant Gem::MARSHAL_SPEC_DIR
/var/lib/snapd/snap/ruby/181/lib/ruby/2.7.0/rubygems.rb:1367: warning: previous definition of MARSHAL_SPEC_DIR was here
/snap/ruby/181/lib/ruby/2.7.0/rubygems/version.rb:158: warning: already initialized constant Gem::Version::VERSION_PATTERN
/var/lib/snapd/snap/ruby/181/lib/ruby/2.7.0/rubygems/version.rb:158: warning: previous definition of VERSION_PATTERN was here
/snap/ruby/181/lib/ruby/2.7.0/rubygems/version.rb:159: warning: already initialized constant Gem::Version::ANCHORED_VERSION_PATTERN
/var/lib/snapd/snap/ruby/181/lib/ruby/2.7.0/rubygems/version.rb:159: warning: previous definition of ANCHORED_VERSION_PATTERN was here
/snap/ruby/181/lib/ruby/2.7.0/rubygems/requirement.rb:14: warning: already initialized constant Gem::Requirement::OPS
/var/lib/snapd/snap/ruby/181/lib/ruby/2.7.0/rubygems/requirement.rb:14: warning: previous definition of OPS was here
/snap/ruby/181/lib/ruby/2.7.0/rubygems/requirement.rb:24: warning: already initialized constant Gem::Requirement::SOURCE_SET_REQUIREMENT
/var/lib/snapd/snap/ruby/181/lib/ruby/2.7.0/rubygems/requirement.rb:24: warning: previous definition of SOURCE_SET_REQUIREMENT was here
/snap/ruby/181/lib/ruby/2.7.0/rubygems/requirement.rb:27: warning: already initialized constant Gem::Requirement::PATTERN_RAW
/var/lib/snapd/snap/ruby/181/lib/ruby/2.7.0/rubygems/requirement.rb:27: warning: previous definition of PATTERN_RAW was here
/snap/ruby/181/lib/ruby/2.7.0/rubygems/requirement.rb:32: warning: already initialized constant Gem::Requirement::PATTERN
/var/lib/snapd/snap/ruby/181/lib/ruby/2.7.0/rubygems/requirement.rb:32: warning: previous definition of PATTERN was here
/snap/ruby/181/lib/ruby/2.7.0/rubygems/requirement.rb:37: warning: already initialized constant Gem::Requirement::DefaultRequirement
/var/lib/snapd/snap/ruby/181/lib/ruby/2.7.0/rubygems/requirement.rb:37: warning: previous definition of DefaultRequirement was here
/snap/ruby/181/lib/ruby/2.7.0/rubygems/requirement.rb:42: warning: already initialized constant Gem::Requirement::DefaultPrereleaseRequirement
/var/lib/snapd/snap/ruby/181/lib/ruby/2.7.0/rubygems/requirement.rb:42: warning: previous definition of DefaultPrereleaseRequirement was here
/snap/ruby/181/lib/ruby/2.7.0/rubygems/requirement.rb:311: warning: already initialized constant Gem::Version::Requirement
/var/lib/snapd/snap/ruby/181/lib/ruby/2.7.0/rubygems/requirement.rb:311: warning: previous definition of Requirement was here
/snap/ruby/181/lib/ruby/2.7.0/rubygems/platform.rb:198: warning: already initialized constant Gem::Platform::RUBY
/var/lib/snapd/snap/ruby/181/lib/ruby/2.7.0/rubygems/platform.rb:198: warning: previous definition of RUBY was here
/snap/ruby/181/lib/ruby/2.7.0/rubygems/platform.rb:204: warning: already initialized constant Gem::Platform::CURRENT
/var/lib/snapd/snap/ruby/181/lib/ruby/2.7.0/rubygems/platform.rb:204: warning: previous definition of CURRENT was here
/snap/ruby/181/lib/ruby/2.7.0/rubygems/stub_specification.rb:10: warning: already initialized constant Gem::StubSpecification::PREFIX
/var/lib/snapd/snap/ruby/181/lib/ruby/2.7.0/rubygems/stub_specification.rb:10: warning: previous definition of PREFIX was here
/snap/ruby/181/lib/ruby/2.7.0/rubygems/stub_specification.rb:13: warning: already initialized constant Gem::StubSpecification::OPEN_MODE
/var/lib/snapd/snap/ruby/181/lib/ruby/2.7.0/rubygems/stub_specification.rb:13: warning: previous definition of OPEN_MODE was here
/snap/ruby/181/lib/ruby/2.7.0/rubygems/stub_specification.rb:20: warning: already initialized constant Gem::StubSpecification::StubLine::NO_EXTENSIONS
/var/lib/snapd/snap/ruby/181/lib/ruby/2.7.0/rubygems/stub_specification.rb:20: warning: previous definition of NO_EXTENSIONS was here
/snap/ruby/181/lib/ruby/2.7.0/rubygems/stub_specification.rb:23: warning: already initialized constant Gem::StubSpecification::StubLine::REQUIRE_PATHS
/var/lib/snapd/snap/ruby/181/lib/ruby/2.7.0/rubygems/stub_specification.rb:23: warning: previous definition of REQUIRE_PATHS was here
/snap/ruby/181/lib/ruby/2.7.0/rubygems/stub_specification.rb:33: warning: already initialized constant Gem::StubSpecification::StubLine::REQUIRE_PATH_LIST
/var/lib/snapd/snap/ruby/181/lib/ruby/2.7.0/rubygems/stub_specification.rb:33: warning: previous definition of REQUIRE_PATH_LIST was here
/snap/ruby/181/lib/ruby/2.7.0/rubygems/user_interaction.rb:565: warning: already initialized constant Gem::StreamUI::ThreadedDownloadReporter::MUTEX
/var/lib/snapd/snap/ruby/181/lib/ruby/2.7.0/rubygems/user_interaction.rb:565: warning: previous definition of MUTEX was here
/snap/ruby/181/lib/ruby/2.7.0/rubygems/specification_policy.rb:7: warning: already initialized constant Gem::SpecificationPolicy::VALID_NAME_PATTERN
/var/lib/snapd/snap/ruby/181/lib/ruby/2.7.0/rubygems/specification_policy.rb:7: warning: previous definition of VALID_NAME_PATTERN was here
/snap/ruby/181/lib/ruby/2.7.0/rubygems/specification_policy.rb:9: warning: already initialized constant Gem::SpecificationPolicy::SPECIAL_CHARACTERS
/var/lib/snapd/snap/ruby/181/lib/ruby/2.7.0/rubygems/specification_policy.rb:9: warning: previous definition of SPECIAL_CHARACTERS was here
/snap/ruby/181/lib/ruby/2.7.0/rubygems/specification_policy.rb:11: warning: already initialized constant Gem::SpecificationPolicy::VALID_URI_PATTERN
/var/lib/snapd/snap/ruby/181/lib/ruby/2.7.0/rubygems/specification_policy.rb:11: warning: previous definition of VALID_URI_PATTERN was here
/snap/ruby/181/lib/ruby/2.7.0/rubygems/specification_policy.rb:13: warning: already initialized constant Gem::SpecificationPolicy::METADATA_LINK_KEYS
/var/lib/snapd/snap/ruby/181/lib/ruby/2.7.0/rubygems/specification_policy.rb:13: warning: previous definition of METADATA_LINK_KEYS was here
/snap/ruby/181/lib/ruby/2.7.0/rubygems/specification_policy.rb:341: warning: already initialized constant Gem::SpecificationPolicy::LAZY
/var/lib/snapd/snap/ruby/181/lib/ruby/2.7.0/rubygems/specification_policy.rb:341: warning: previous definition of LAZY was here
/snap/ruby/181/lib/ruby/2.7.0/rubygems/specification_policy.rb:342: warning: already initialized constant Gem::SpecificationPolicy::LAZY_PATTERN
/var/lib/snapd/snap/ruby/181/lib/ruby/2.7.0/rubygems/specification_policy.rb:342: warning: previous definition of LAZY_PATTERN was here
/snap/ruby/181/lib/ruby/2.7.0/rubygems/specification_policy.rb:343: warning: already initialized constant Gem::SpecificationPolicy::HOMEPAGE_URI_PATTERN
/var/lib/snapd/snap/ruby/181/lib/ruby/2.7.0/rubygems/specification_policy.rb:343: warning: previous definition of HOMEPAGE_URI_PATTERN was here
/snap/ruby/181/lib/ruby/2.7.0/rubygems/specification.rb:51: warning: already initialized constant Gem::Specification::NONEXISTENT_SPECIFICATION_VERSION
/var/lib/snapd/snap/ruby/181/lib/ruby/2.7.0/rubygems/specification.rb:51: warning: previous definition of NONEXISTENT_SPECIFICATION_VERSION was here
/snap/ruby/181/lib/ruby/2.7.0/rubygems/specification.rb:74: warning: already initialized constant Gem::Specification::CURRENT_SPECIFICATION_VERSION
/var/lib/snapd/snap/ruby/181/lib/ruby/2.7.0/rubygems/specification.rb:74: warning: previous definition of CURRENT_SPECIFICATION_VERSION was here
/snap/ruby/181/lib/ruby/2.7.0/rubygems/specification.rb:80: warning: already initialized constant Gem::Specification::SPECIFICATION_VERSION_HISTORY
/var/lib/snapd/snap/ruby/181/lib/ruby/2.7.0/rubygems/specification.rb:80: warning: previous definition of SPECIFICATION_VERSION_HISTORY was here
/snap/ruby/181/lib/ruby/2.7.0/rubygems/specification.rb:98: warning: already initialized constant Gem::Specification::MARSHAL_FIELDS
/var/lib/snapd/snap/ruby/181/lib/ruby/2.7.0/rubygems/specification.rb:98: warning: previous definition of MARSHAL_FIELDS was here
/snap/ruby/181/lib/ruby/2.7.0/rubygems/specification.rb:107: warning: already initialized constant Gem::Specification::TODAY
/var/lib/snapd/snap/ruby/181/lib/ruby/2.7.0/rubygems/specification.rb:107: warning: previous definition of TODAY was here
/snap/ruby/181/lib/ruby/2.7.0/rubygems/specification.rb:110: warning: already initialized constant Gem::Specification::LOAD_CACHE
/var/lib/snapd/snap/ruby/181/lib/ruby/2.7.0/rubygems/specification.rb:110: warning: previous definition of LOAD_CACHE was here
/snap/ruby/181/lib/ruby/2.7.0/rubygems/specification.rb:112: warning: already initialized constant Gem::Specification::LOAD_CACHE_MUTEX
/var/lib/snapd/snap/ruby/181/lib/ruby/2.7.0/rubygems/specification.rb:112: warning: previous definition of LOAD_CACHE_MUTEX was here
/snap/ruby/181/lib/ruby/2.7.0/rubygems/specification.rb:116: warning: already initialized constant Gem::Specification::VALID_NAME_PATTERN
/var/lib/snapd/snap/ruby/181/lib/ruby/2.7.0/rubygems/specification.rb:116: warning: previous definition of VALID_NAME_PATTERN was here
/snap/ruby/181/lib/ruby/2.7.0/rubygems/specification.rb:167: warning: already initialized constant Gem::Specification::INITIALIZE_CODE_FOR_DEFAULTS
/var/lib/snapd/snap/ruby/181/lib/ruby/2.7.0/rubygems/specification.rb:167: warning: previous definition of INITIALIZE_CODE_FOR_DEFAULTS was here
/snap/ruby/181/lib/ruby/2.7.0/rubygems/specification.rb:192: warning: already initialized constant Gem::Specification::NOT_FOUND
/var/lib/snapd/snap/ruby/181/lib/ruby/2.7.0/rubygems/specification.rb:192: warning: previous definition of NOT_FOUND was here
/snap/ruby/181/lib/ruby/2.7.0/rubygems/specification.rb:835: warning: already initialized constant Gem::Specification::EMPTY
/var/lib/snapd/snap/ruby/181/lib/ruby/2.7.0/rubygems/specification.rb:835: warning: previous definition of EMPTY was here
/snap/ruby/181/lib/ruby/2.7.0/rubygems/specification.rb:1673: warning: already initialized constant Gem::Specification::DateLike
/var/lib/snapd/snap/ruby/181/lib/ruby/2.7.0/rubygems/specification.rb:1673: warning: previous definition of DateLike was here
/snap/ruby/181/lib/ruby/2.7.0/rubygems/specification.rb:1678: warning: already initialized constant Gem::Specification::DateTimeFormat
/var/lib/snapd/snap/ruby/181/lib/ruby/2.7.0/rubygems/specification.rb:1678: warning: previous definition of DateTimeFormat was here
/snap/ruby/181/lib/ruby/2.7.0/rubygems/exceptions.rb:292: warning: already initialized constant Gem::UnsatisfiableDepedencyError
/var/lib/snapd/snap/ruby/181/lib/ruby/2.7.0/rubygems/exceptions.rb:292: warning: previous definition of UnsatisfiableDepedencyError was here
Traceback (most recent call last):
        5: from /var/lib/snapd/snap/ruby/181/bin/gem:8:in `<main>'
        4: from /var/lib/snapd/snap/ruby/181/lib/ruby/2.7.0/rubygems/core_ext/kernel_require.rb:72:in `require'
        3: from /var/lib/snapd/snap/ruby/181/lib/ruby/2.7.0/rubygems/core_ext/kernel_require.rb:72:in `require'
        2: from /snap/ruby/181/lib/ruby/2.7.0/rubygems.rb:1397:in `<top (required)>'
        1: from /var/lib/snapd/snap/ruby/181/lib/ruby/2.7.0/rubygems/core_ext/kernel_require.rb:92:in `require'
/var/lib/snapd/snap/ruby/181/lib/ruby/2.7.0/rubygems/core_ext/kernel_require.rb:92:in `require': cannot load such file -- rubygems/defaults/operating_system (LoadError)
        14: from /var/lib/snapd/snap/ruby/181/bin/gem:8:in `<main>'
        13: from /var/lib/snapd/snap/ruby/181/lib/ruby/2.7.0/rubygems/core_ext/kernel_require.rb:72:in `require'
        12: from /var/lib/snapd/snap/ruby/181/lib/ruby/2.7.0/rubygems/core_ext/kernel_require.rb:72:in `require'
        11: from /snap/ruby/181/lib/ruby/2.7.0/rubygems.rb:1397:in `<top (required)>'
        10: from /var/lib/snapd/snap/ruby/181/lib/ruby/2.7.0/rubygems/core_ext/kernel_require.rb:156:in `require'
         9: from /var/lib/snapd/snap/ruby/181/lib/ruby/2.7.0/rubygems/core_ext/kernel_require.rb:161:in `rescue in require'
         8: from /snap/ruby/181/lib/ruby/2.7.0/rubygems.rb:204:in `try_activate'
         7: from /snap/ruby/181/lib/ruby/2.7.0/rubygems/specification.rb:996:in `find_by_path'
         6: from /snap/ruby/181/lib/ruby/2.7.0/rubygems/specification.rb:815:in `stubs'
         5: from /snap/ruby/181/lib/ruby/2.7.0/rubygems/specification.rb:932:in `dirs'
         4: from /snap/ruby/181/lib/ruby/2.7.0/rubygems.rb:420:in `path'
         3: from /snap/ruby/181/lib/ruby/2.7.0/rubygems.rb:374:in `paths'
         2: from /var/lib/snapd/snap/ruby/181/lib/ruby/2.7.0/rubygems/core_ext/kernel_require.rb:72:in `require'
         1: from /var/lib/snapd/snap/ruby/181/lib/ruby/2.7.0/rubygems/core_ext/kernel_require.rb:72:in `require'
/snap/ruby/181/lib/ruby/2.7.0/rubygems/path_support.rb:7:in `<top (required)>': uninitialized constant Gem::PathSupport (NameError)

The reproducing procedure is as follows.

sudo yum upgrade -y
# reboot here
sudo yum install -y epel-release
sudo yum install -y snapd
sudo systemctl enable --now snapd.socket
sudo ln -s /var/lib/snapd/snap /snap
# logout and login here to reflect the PATH
sudo snap install ruby --classic --channel=2.7/stable
gem -v

This does not happen in 2.6/stable. Also, this does not happen on Ubuntu.

Reproduziere den Fehler mit dem 2.7/stable-Snap auf CentOS 7 oder 8, beginne mit dem Gem-Einstiegspunkt und vergleiche die im Bericht gezeigten RubyGems-Pfade /snap/ruby und /var/lib/snapd/snap. Prüfe gem, bundle, irb, rake, rdoc und ri; abgeschlossen ist die Aufgabe, wenn diese Befehle keine duplicate-constant-Warnungen mehr ausgeben.