test: use a more verbose output in the test
While debugging some test failure, I released the test never checks if the
relevant changesets were preserved. So I am updating the test from `hg parents`
usage to `hg log -G` with a special template. This increase the area covered by
the test and clarify the test failures.
#require execbit
$ hg init repo
$ cd repo
$ echo foo > foo
$ chmod 644 foo
$ hg ci -qAm '644'
$ chmod 755 foo
$ hg ci -qAm '755'
reverting to rev 0
$ hg revert -a -r 0
reverting foo
$ hg st
M foo
$ hg diff --git
diff --git a/foo b/foo
old mode 100755
new mode 100644
$ cd ..