Fix Mercurial version format strings in unittest

In hgtests.py we let hg create the timestamp in UTC but create the
reference timestamp in the local timezone. Since GIT is giving us the
localtime in the test by default lets do the same thing for Mercurial.

Signed-off-by: Jan Blunck <jblunck@infradead.org>
Merge pull request #62 from jblunck/fix_hgtest

Fix Mercurial version format strings in unittest