sideband: color lines with keyword only

When bf1a11f0a1 (sideband: highlight keywords in remote sideband output,
2018-08-07) was introduced, it was carefully considered which strings
would be highlighted. However 59a255aef0 (sideband: do not read beyond
the end of input, 2018-08-18) brought in a regression that the original
did not test for. A line containing only the keyword and nothing else
("SUCCESS") should still be colored.

Signed-off-by: Stefan Beller <sbeller@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
diff --git a/t/t5409-colorize-remote-messages.sh b/t/t5409-colorize-remote-messages.sh
index f81b681..2a8c449 100755
--- a/t/t5409-colorize-remote-messages.sh
+++ b/t/t5409-colorize-remote-messages.sh
@@ -17,6 +17,7 @@
 	echo " " "error: leading space"
 	echo "    "
 	echo Err
+	echo SUCCESS
 	exit 0
 	EOF
 	echo 1 >file &&
@@ -35,6 +36,7 @@
 	grep "<BOLD;RED>error<RESET>: error" decoded &&
 	grep "<YELLOW>hint<RESET>:" decoded &&
 	grep "<BOLD;GREEN>success<RESET>:" decoded &&
+	grep "<BOLD;GREEN>SUCCESS<RESET>" decoded &&
 	grep "<BOLD;YELLOW>warning<RESET>:" decoded
 '