Teach all of log family --left-right output.

This makes reviewing

     git log --left-right --merge --no-merges -p

a lot more pleasant.
Signed-off-by: NJunio C Hamano <junkio@cox.net>

builtin-rev-list.c

@@ -45,7 +45,6 @@ static int bisect_list;
 static int show_timestamp;
 static int hdr_termination;
 static const char *header_prefix;
-static int show_left_right;
 
 static void show_commit(struct commit *commit)
 {
@@ -55,7 +54,7 @@ static void show_commit(struct commit *commit)
 		fputs(header_prefix, stdout);
 	if (commit->object.flags & BOUNDARY)
 		putchar('-');
-	else if (show_left_right) {
+	else if (revs.left_right) {
 		if (commit->object.flags & SYMMETRIC_LEFT)
 			putchar('<');
 		else
@@ -247,10 +246,6 @@ int cmd_rev_list(int argc, const char **argv, const char *prefix)
 			bisect_list = 1;
 			continue;
 		}
-		if (!strcmp(arg, "--left-right")) {
-			show_left_right = 1;
-			continue;
-		}
 		if (!strcmp(arg, "--stdin")) {
 			if (read_from_stdin++)
 				die("--stdin given twice?");

log-tree.c

@@ -114,6 +114,14 @@ void show_log(struct rev_info *opt, const char *sep)
 
 	opt->loginfo = NULL;
 	if (!opt->verbose_header) {
+		if (opt->left_right) {
+			if (commit->object.flags & BOUNDARY)
+				putchar('-');
+			else if (commit->object.flags & SYMMETRIC_LEFT)
+				putchar('<');
+			else
+				putchar('>');
+		}
 		fputs(diff_unique_abbrev(commit->object.sha1, abbrev_commit), stdout);
 		if (opt->parents)
 			show_parents(commit, abbrev_commit);
@@ -192,10 +200,20 @@ void show_log(struct rev_info *opt, const char *sep)
 			opt->diffopt.stat_sep = buffer;
 		}
 	} else {
-		printf("%s%s%s",
-		       diff_get_color(opt->diffopt.color_diff, DIFF_COMMIT),
-		       opt->commit_format == CMIT_FMT_ONELINE ? "" : "commit ",
-		       diff_unique_abbrev(commit->object.sha1, abbrev_commit));
+		fputs(diff_get_color(opt->diffopt.color_diff, DIFF_COMMIT),
+		      stdout);
+		if (opt->commit_format != CMIT_FMT_ONELINE)
+			fputs("commit ", stdout);
+		if (opt->left_right) {
+			if (commit->object.flags & BOUNDARY)
+				putchar('-');
+			else if (commit->object.flags & SYMMETRIC_LEFT)
+				putchar('<');
+			else
+				putchar('>');
+		}
+		fputs(diff_unique_abbrev(commit->object.sha1, abbrev_commit),
+		      stdout);
 		if (opt->parents)
 			show_parents(commit, abbrev_commit);
 		if (parent)

revision.c

@@ -853,6 +853,10 @@ int setup_revisions(int argc, const char **argv, struct rev_info *revs, const ch
 				revs->boundary = 1;
 				continue;
 			}
+			if (!strcmp(arg, "--left-right")) {
+				revs->left_right = 1;
+				continue;
+			}
 			if (!strcmp(arg, "--objects")) {
 				revs->tag_objects = 1;
 				revs->tree_objects = 1;

revision.h

@@ -41,6 +41,7 @@ struct rev_info {
 			limited:1,
 			unpacked:1, /* see also ignore_packed below */
 			boundary:1,
+			left_right:1,
 			parents:1;
 
 	/* Diff flags */