fix "git -c" parsing of values with equals signs

If you do something like:

  git -c core.foo="value with = in it" ...

we would split your option on "=" into three fields and
throw away the third one. With this patch we correctly take
everything after the first "=" as the value (keys cannot
have an equals sign in them, so the parsing is unambiguous).

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

config.c

@@ -45,7 +45,7 @@ static int git_config_parse_parameter(const char *text,
 	struct strbuf tmp = STRBUF_INIT;
 	struct strbuf **pair;
 	strbuf_addstr(&tmp, text);
-	pair = strbuf_split(&tmp, '=');
+	pair = strbuf_split_max(&tmp, '=', 2);
 	if (pair[0]->len && pair[0]->buf[pair[0]->len - 1] == '=')
 		strbuf_setlen(pair[0], pair[0]->len - 1);
 	strbuf_trim(pair[0]);

t/t1300-repo-config.sh

@@ -904,4 +904,10 @@ test_expect_success 'git -c works with aliases of builtins' '
 	test_cmp expect actual
 '
 
+test_expect_success 'git -c does not split values on equals' '
+	echo "value with = in it" >expect &&
+	git -c core.foo="value with = in it" config core.foo >actual &&
+	test_cmp expect actual
+'
+
 test_done