t8001/t8002: blame: demonstrate acceptance of bogus -L,+0 and -L,-0

Empty ranges -L,+0 and -L,-0 are nonsensical in the context of blame yet
they are accepted. They should be errors. Demonstrate this shortcoming.

Signed-off-by: Eric Sunshine <sunshine@sunshineco.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

t/annotate-tests.sh

@@ -185,6 +185,10 @@ test_expect_success 'blame -L Y,X (undocumented)' '
 	check_count -L6,3 B 1 B1 1 B2 1 D 1
 '
 
+test_expect_failure 'blame -L ,+0' '
+	test_must_fail $PROG -L,+0 file
+'
+
 test_expect_success 'blame -L X,+0' '
 	test_must_fail $PROG -L1,+0 file
 '
@@ -197,6 +201,10 @@ test_expect_success 'blame -L X,+N' '
 	check_count -L3,+4 B 1 B1 1 B2 1 D 1
 '
 
+test_expect_failure 'blame -L ,-0' '
+	test_must_fail $PROG -L,-0 file
+'
+
 test_expect_success 'blame -L X,-0' '
 	test_must_fail $PROG -L1,-0 file
 '