parse_color: fix return value for numeric color values 0-8

When commit 695d95df refactored the color parsing, it missed
a "return 0" when parsing literal numbers 0-8 (which
represent basic ANSI colors), leading us to report these
colors as an error.
Signed-off-by: NJeff King <peff@peff.net>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

color.c

@@ -112,6 +112,7 @@ static int parse_color(struct color *out, const char *name, int len)
 		} else if (val < 8) {
 			out->type = COLOR_ANSI;
 			out->value = val;
+			return 0;
 		} else if (val < 256) {
 			out->type = COLOR_256;
 			out->value = val;

t/t4026-color.sh

@@ -60,6 +60,10 @@ test_expect_success 'absurdly long color specification' '
 	  "[1;2;4;5;7;22;24;25;27;38;2;255;255;255;48;2;255;255;255m"
 '
 
+test_expect_success '0-7 are aliases for basic ANSI color names' '
+	color "0 7" "[30;47m"
+'
+
 test_expect_success '256 colors' '
 	color "254 bold 255" "[1;38;5;254;48;5;255m"
 '