t7001 (mv): add missing &&

Also, prefix an expected-to-fail git mv command with 'test_must_fail'.

Acked-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Reviewed-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

t/t7001-mv.sh

@@ -61,7 +61,7 @@ test_expect_success \
 test_expect_success \
     'checking -f on untracked file with existing target' \
     'touch path0/untracked1 &&
-     git mv -f untracked1 path0
+     test_must_fail git mv -f untracked1 path0 &&
      test ! -f .git/index.lock &&
      test -f untracked1 &&
      test -f path0/untracked1'