Add `log.decorate' configuration variable.

This alows the 'git-log --decorate' to be enabled by default so that normal
log outout contains ant ref names of commits that are shown.

Signed-off-by: Steven Drake <sdrake@xnet.co.nz>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Documentation/config.txt

@@ -1232,6 +1232,13 @@ log.date::
 	following alternatives: {relative,local,default,iso,rfc,short}.
 	See linkgit:git-log[1].
 
+log.decorate::
+	Print out the ref names of any commits that are shown by the log
+	command. If 'short' is specified, the ref name prefixes 'refs/heads/',
+	'refs/tags/' and 'refs/remotes/' will not be printed. If 'full' is
+	specified, the full ref name (including prefix) will be printed.
+	This is the same as the log commands '--decorate' option.
+
 log.showroot::
 	If true, the initial commit will be shown as a big creation event.
 	This is equivalent to a diff against an empty tree.

builtin-log.c

@@ -24,6 +24,7 @@
 static const char *default_date_mode = NULL;
 
 static int default_show_root = 1;
+static int decoration_style = 0;
 static const char *fmt_patch_subject_prefix = "PATCH";
 static const char *fmt_pretty;
 
@@ -35,7 +36,6 @@ static void cmd_log_init(int argc, const char **argv, const char *prefix,
 		      struct rev_info *rev)
 {
 	int i;
-	int decoration_style = 0;
 
 	rev->abbrev = DEFAULT_ABBREV;
 	rev->commit_format = CMIT_FMT_DEFAULT;
@@ -252,6 +252,13 @@ static int git_log_config(const char *var, const char *value, void *cb)
 		return git_config_string(&fmt_patch_subject_prefix, var, value);
 	if (!strcmp(var, "log.date"))
 		return git_config_string(&default_date_mode, var, value);
+	if (!strcmp(var, "log.decorate")) {
+		if (!strcmp(value, "full"))
+			decoration_style = DECORATE_FULL_REFS;
+		else if (!strcmp(value, "short"))
+			decoration_style = DECORATE_SHORT_REFS;
+		return 0;
+	}
 	if (!strcmp(var, "log.showroot")) {
 		default_show_root = git_config_bool(var, value);
 		return 0;