Errors with Mackup

I am trying to use Keybase with Mackup (https://github.com/lra/mackup), but I am getting some errors:

Backing up .subversion ... Traceback (most recent call last): File "/usr/local/Cellar/mackup/0.8.16/libexec/bin/mackup", line 9, in load_entry_point('mackup==0.8.16', 'console_scripts', 'mackup')() File "/usr/local/Cellar/mackup/0.8.16/libexec/lib/python2.7/site-packages/mackup/main.py", line 90, in main app.backup() File "/usr/local/Cellar/mackup/0.8.16/libexec/lib/python2.7/site-packages/mackup/application.py", line 114, in backup utils.copy(home_filepath, mackup_filepath) File "/usr/local/Cellar/mackup/0.8.16/libexec/lib/python2.7/site-packages/mackup/utils.py", line 105, in copy shutil.copytree(src, dst) File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/shutil.py", line 208, in copytree raise Error, errors shutil.Error: [('/Users/andrea/.subversion/auth/svn.simple', '/keybase/private/andreadellacorte/Mackup/.subversion/auth/svn.simple', "[Errno 78] Function not implemented: '/keybase/private/andreadellacorte/Mackup/.subversion/auth/svn.simple'"), ('/Users/andrea/.subversion/auth/svn.ssl.client-passphrase', '/keybase/private/andreadellacorte/Mackup/.subversion/auth/svn.ssl.client-passphrase', "[Errno 78] Function not implemented: '/keybase/private/andreadellacorte/Mackup/.subversion/auth/svn.ssl.client-passphrase'"), ('/Users/andrea/.subversion/auth/svn.ssl.server', '/keybase/private/andreadellacorte/Mackup/.subversion/auth/svn.ssl.server', "[Errno 78] Function not implemented: '/keybase/private/andreadellacorte/Mackup/.subversion/auth/svn.ssl.server'"), ('/Users/andrea/.subversion/auth/svn.username', '/keybase/private/andreadellacorte/Mackup/.subversion/auth/svn.username', "[Errno 78] Function not implemented: '/keybase/private/andreadellacorte/Mackup/.subversion/auth/svn.username'"), ('/Users/andrea/.subversion/auth', '/keybase/private/andreadellacorte/Mackup/.subversion/auth', "[Errno 78] Function not implemented: '/keybase/private/andreadellacorte/Mackup/.subversion/auth'"), ('/Users/andrea/.subversion', '/keybase/private/andreadellacorte/Mackup/.subversion', "[Errno 78] Function not implemented: '/keybase/private/andreadellacorte/Mackup/.subversion'")]

Reproduce the Mackup backup of .subversion to the Keybase path, then inspect mackup/application.py, mackup/utils.py, and the mackup console entry point shown in the traceback. Determine whether the failure is actionable in Mackup or Keybase; done means the cause and a supported resolution are established.

Written by the indexing model from the issue text.