Fixes a number of issues with the git provider. remote_branch_revision?
method was always returning true because it would always at least return
something, even if that something was a zero length array. You normally
don't desire a tag to become a branch since it creates ambiguity so I
removed that. latest method had no concept of (no branch) and so would
fail if you switched to a remote branch or a tag. Then finally
revision sha1 returned by 'git rev-parse' for tags is not the revision
of the commit the tag represents. We have to use 'git show' and do
some text parsing to actually figure out which commit goes with which
tag.
8e51aebd4c