Don't format version to 5 characters in new version message

Change-Id: I6c734170173f77a6fef0678f189e198bdaeec425
Reviewed-on: https://gerrit-review.googlesource.com/c/git-repo/+/254668


Tested-by: David Pursehouse <dpursehouse@collab.net>
Reviewed-by: Mike Frysinger <vapier@google.com>