test: use a different timestamp for the updated file
In the test we want to trigger a write after the underlying dirstate changed. To
do so, we need a write. And as we are about to make dirstate update smarter we
need to meddle with the script a bit to make sure there will be a write.
Differential Revision: https://phab.mercurial-scm.org/D11793
$ LANG=nonexistent LC_ALL=nonexistent LANGUAGE=nonexistent hg version -q
Mercurial Distributed SCM (version *) (glob)