t: allow 'scalar' in test_must_fail

This will enable scalar tests to use the test_must_fail helper, when
necessary.

Signed-off-by: Derrick Stolee <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>

Author: derrickstolee

t/test-lib-functions.sh

@@ -1016,7 +1016,7 @@ test_must_fail_acceptable () {
 	fi
 
 	case "$1" in
-	git|__git*|test-tool|test_terminal)
+	git|__git*|scalar|test-tool|test_terminal)
 		return 0
 		;;
 	*)