Updated status to show 'Not currently on any branch' in red

This provides additional warning to users when attempting to
commit to a detached HEAD. It is configurable in color.status.nobranch.

Signed-off-by: Chris Parsons <chris@edendevelopment.co.uk>
Acked-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Documentation/config.txt

@@ -523,8 +523,10 @@ color.status.<slot>::
 	one of `header` (the header text of the status message),
 	`added` or `updated` (files which are added but not committed),
 	`changed` (files which are changed but not added in the index),
-	or `untracked` (files which are not tracked by git). The values of
-	these variables may be specified as in color.branch.<slot>.
+	`untracked` (files which are not tracked by git), or
+	`nobranch` (the color the 'no branch' warning is shown in, defaulting
+	to red). The values of these variables may be specified as in
+	color.branch.<slot>.
 
 commit.template::
 	Specify a file to use as the template for new commit messages.

wt-status.c

@@ -18,6 +18,7 @@ static char wt_status_colors[][COLOR_MAXLEN] = {
 	"\033[32m", /* WT_STATUS_UPDATED: green */
 	"\033[31m", /* WT_STATUS_CHANGED: red */
 	"\033[31m", /* WT_STATUS_UNTRACKED: red */
+	"\033[31m", /* WT_STATUS_NOBRANCH: red */
 };
 
 static const char use_add_msg[] =
@@ -38,6 +39,8 @@ static int parse_status_slot(const char *var, int offset)
 		return WT_STATUS_CHANGED;
 	if (!strcasecmp(var+offset, "untracked"))
 		return WT_STATUS_UNTRACKED;
+	if (!strcasecmp(var+offset, "nobranch"))
+		return WT_STATUS_NOBRANCH;
 	die("bad config variable '%s'", var);
 }
 
@@ -314,19 +317,21 @@ static void wt_status_print_verbose(struct wt_status *s)
 void wt_status_print(struct wt_status *s)
 {
 	unsigned char sha1[20];
-	s->is_initial = get_sha1(s->reference, sha1) ? 1 : 0;
+	const char *branch_color = color(WT_STATUS_HEADER);
 
+	s->is_initial = get_sha1(s->reference, sha1) ? 1 : 0;
 	if (s->branch) {
 		const char *on_what = "On branch ";
 		const char *branch_name = s->branch;
 		if (!prefixcmp(branch_name, "refs/heads/"))
 			branch_name += 11;
 		else if (!strcmp(branch_name, "HEAD")) {
 			branch_name = "";
+			branch_color = color(WT_STATUS_NOBRANCH);
 			on_what = "Not currently on any branch.";
 		}
-		color_fprintf_ln(s->fp, color(WT_STATUS_HEADER),
-			"# %s%s", on_what, branch_name);
+		color_fprintf(s->fp, color(WT_STATUS_HEADER), "# ");
+		color_fprintf_ln(s->fp, branch_color, "%s%s", on_what, branch_name);
 	}
 
 	if (s->is_initial) {

wt-status.h

@@ -8,6 +8,7 @@ enum color_wt_status {
 	WT_STATUS_UPDATED,
 	WT_STATUS_CHANGED,
 	WT_STATUS_UNTRACKED,
+	WT_STATUS_NOBRANCH,
 };
 
 struct wt_status {