t9164: use test_must_fail only on git commands

The `test_must_fail` function should only be used for git commands;
we are not in the business of catching segmentation fault by external
commands.  Shell helper functions test_cmp and svn_cmd used in this
script are wrappers around external commands, so just use `! cmd`
instead of `test_must_fail cmd`

Signed-off-by: Denton Liu <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>

Author: Denton-L

t/t9164-git-svn-dcommit-concurrent.sh

@@ -92,7 +92,7 @@ test_expect_success 'check if post-commit hook creates a concurrent commit' '
 		echo 1 >> file &&
 		svn_cmd commit -m "changing file" &&
 		svn_cmd up &&
-		test_must_fail test_cmp auto_updated_file au_file_saved
+		! test_cmp auto_updated_file au_file_saved
 	)
 '
 
@@ -103,7 +103,7 @@ test_expect_success 'check if pre-commit hook fails' '
 		echo 2 >> file &&
 		svn_cmd commit -m "changing file once again" &&
 		echo 3 >> file &&
-		test_must_fail svn_cmd commit -m "this commit should fail" &&
+		! svn_cmd commit -m "this commit should fail" &&
 		svn_cmd revert file
 	)
 '