_get_name_from_path() in Lib/unittest/loader.py fails when src path contains symlinks

Bug report

Bug description:

This is conceptually somewhat similar to gh-148314

When the path to the source tree is via a symlink, an alternate path to the same will cause _get_name_from_path() to assert, thinking the supplied path is not a sub-path of the src tree. During the run of unittest's test suite, "." is passed as a path which is resolved to an absolute path - which of course doesn't match a symlinked path.

CPython versions tested on:

CPython main branch

Operating systems tested on:

macOS

Linked PRs

• gh-149143

從 Lib/unittest/loader.py 中的 _get_name_from_path() 開始，然後使用透過 symlink 到達的原始碼樹路徑執行 unittest 測試套件。完成標準是替代路徑不再觸發子路徑 assertion，且相關的回歸測試涵蓋通過；gh-149143 已經與此 issue 關聯。