This is probably untranslatable even in English, since we would use "a git working copy" but "an svn working copy" and "an hg working copy" (at least, the way I pronounce them). The VCS type constants also aren't very human readable.

Consider restoring the "git" hardcode for now, or the "right" version of this is probably:

switch ($vcs_type) {
  pht('blah blah full string for git');
  pht('blah blah full string for svn');
  pht('blah blah full string for hg');
}