The last two tests here were always supposed to fail in the sense
that, according to code and documentation, mktree should read non-recursive
ls-tree output, but not recursive one, and therefore explicitely refuses
to deal with slashes.
Adjust the test (must_fail) so that it succeeds when mktree dies on
slashes.
Signed-off-by: Michael J Gruber <git@drmicha.warpmail.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>