SVN revision selection confused by cherry-picks

[ColMelvin]

A commit that is not in the SVN tree but does contain the "git-svn-id:" line (in the git commit) can be incorrectly identified as the desired SVN revision, despite not actually being in the SVN tree. This includes the special revisions, like BASE.

This is similar to the issues that older "git-svn" scripts had with cherry-picked revisions already in the SVN repository (when the git commit retained the git-svn-id: line).

[ColMelvin]

The git-svn script identifies cherry-picks using the .rev_map file that it maintains per branch. This file stores the Git commit hash for each SVN revision in that branch. Thus, if the SVN revision is extracted from a commit and it doesn't match the hash stored in the .rev_map, then this clearly isn't the original commit - it must be a cherry-pick. Or so the implementation goes...

By pulling in Git::SVN, this could be accomplished using an existing mechanism.