This test case would have caught the bug fixed by revision
c23290d5.

It puts various forms of $Id$ into a file in the repository,
without allowing git to collapse them to uniformity.  Then enables the
$Id$ expansion on checkout, and checks that what is checked out has
coped with the various forms.
Signed-off-by: NAndy Parkins <andyparkins@gmail.com>
Signed-off-by: NJunio C Hamano <junkio@cox.net>