[PATCH] builtin/config.c: don't print a newline with --color

[Taylor Blau <me@ttaylorr.com>]

Invocations of 'git config <name>' print a trailing newline after
writing the value assigned to the given configuration variable.

This has an unexpected interaction with 63e2a0f8e9 (builtin/config:
introduce `color` type specifier, 2018-04-09), which causes a newline to
be printed after a color's ANSI escape sequence.

In this case, printing a terminating newline is not desirable. Callers
may want to print out such a configuration variable in a sub-shell in
order to color something else, in which case they certainly don't want a
newline.

This bug has survived because there was never a test that would have
caught it. The old test used 'test_decode_color', which checks that its
input begins with a color, but stops parsing once it has parsed a single
color successfully. In this case, it was ignoring the trailing '\n'.

To do what callers expect, only print a newline when the type is not
'color', and print the escape sequence itself for an exact comparison.

Signed-off-by: Taylor Blau <me@ttaylorr.com>
---
 builtin/config.c  | 3 ++-
 t/t1300-config.sh | 5 ++---
 2 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/builtin/config.c b/builtin/config.c
index 98d65bc0ad..c8f088af38 100644
--- a/builtin/config.c
+++ b/builtin/config.c
@@ -258,7 +258,8 @@ static int format_config(struct strbuf *buf, const char *key_, const char *value
 				strbuf_setlen(buf, buf->len - 1);
 		}
 	}
-	strbuf_addch(buf, term);
+	if (type != TYPE_COLOR)
+		strbuf_addch(buf, term);
 	return 0;
 }
 
diff --git a/t/t1300-config.sh b/t/t1300-config.sh
index 428177c390..ec1b3a852d 100755
--- a/t/t1300-config.sh
+++ b/t/t1300-config.sh
@@ -907,9 +907,8 @@ test_expect_success 'get --expiry-date' '
 test_expect_success 'get --type=color' '
 	rm .git/config &&
 	git config foo.color "red" &&
-	git config --get --type=color foo.color >actual.raw &&
-	test_decode_color <actual.raw >actual &&
-	echo "<RED>" >expect &&
+	printf "\\033[31m" >expect &&
+	git config --get --type=color foo.color >actual &&
 	test_cmp expect actual
 '
 
-- 
2.20.1