pickaxe tests: add missing test for --no-pickaxe-regex being an error

Add a missing test for --no-pickaxe-regex. This has been an error ever
since before the -S or -G options were added, or since
7ae0b0c (git-log (internal): more options., 2006-03-01).

The reason for adding this test is that Junio suggested in [1] in
response to a later test addition in this series that it might be good
to support --no-pickaxe-regex in combination with -G. This would allow
for fixed-string searching with -G, similr to grep's --fixed-strings
mode.

I agree that that would make sense if anyone would like to implement
it, but since it dies right now let's first add this test to assert
the existing long-standing behavior. We can always add support for
--[no-]pickaxe-regex in combination with -G at some later date.

1. http://lore.kernel.org/git/[email protected]

Signed-off-by: Ævar Arnfjörð Bjarmason <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>

Author: avar

t/t4209-log-pickaxe.sh

@@ -66,6 +66,18 @@ test_expect_success 'usage' '
 	grep "mutually exclusive" err
 '
 
+test_expect_success 'usage: --no-pickaxe-regex' '
+	cat >expect <<-\EOF &&
+	fatal: unrecognized argument: --no-pickaxe-regex
+	EOF
+
+	test_expect_code 128 git log -Sstring --no-pickaxe-regex 2>actual &&
+	test_cmp expect actual &&
+
+	test_expect_code 128 git log -Gstring --no-pickaxe-regex 2>err &&
+	test_cmp expect actual
+'
+
 test_log	expect_initial	--grep initial
 test_log	expect_nomatch	--grep InItial
 test_log_icase	expect_initial	--grep InItial