fixup! survey: clearly note the experimental nature in the output

This is needed to let the tests pass (which assume that the output can
be completely empty).

Signed-off-by: Johannes Schindelin <[email protected]>

Author: dscho

builtin/survey.c

@@ -893,9 +893,10 @@ int cmd_survey(int argc, const char **argv, const char *prefix)
 	if (argc == 2 && !strcmp(argv[1], "-h"))
 		usage_with_options(survey_usage, survey_options);
 
-	color_fprintf_ln(stderr,
-			 want_color_fd(2, GIT_COLOR_AUTO) ? GIT_COLOR_YELLOW : "",
-			 "(THIS IS EXPERIMENTAL, EXPECT THE OUTPUT FORMAT TO CHANGE!)");
+	if (isatty(2))
+		color_fprintf_ln(stderr,
+				 want_color_fd(2, GIT_COLOR_AUTO) ? GIT_COLOR_YELLOW : "",
+				 "(THIS IS EXPERIMENTAL, EXPECT THE OUTPUT FORMAT TO CHANGE!)");
 
 	ctx.repo = the_repository;