git-fsck, of all tools, has very few tests. This adds some more:
* a corrupted object;
* a branch pointing to a non-commit;
* a tag pointing to a nonexistent object;
* and a tag pointing to an object of a type other than what the tag
itself claims.
Only the first two are caught. At least the third probably should,
too, but currently slips through.
Signed-off-by: Thomas Rast <trast@student.ethz.ch> Signed-off-by: Junio C Hamano <gitster@pobox.com>