Now git-topic is a bit more usable and close enough to TO script.

TO

@@ -111,8 +111,9 @@ Using Topic Branches
 
 Some important disciplines first.
 
- * Once a topic branch forks from "master", never merge "master"
-   updates into the topic branch.
+ * Once a topic branch forks from "master", avoid merging "master"
+   updates into the topic branch unless necessary to resolve conflicts
+   early.
 
  * Once a topic branch is fully cooked and merged into "master",
    delete it.  If you need to build on top of it to correct

git-topic.perl

@@ -25,9 +25,9 @@ if (@custom_stage) { @stage = @custom_stage; }
 if (@custom_mark) { @mark = @custom_mark; }
 
 sub read_revs_short {
-	my ($bottom, $top) = @_;
+	my (@args) = @_;
 	my @revs;
-	open(REVS, '-|', qw(git rev-list --no-merges), "$bottom..$top")
+	open(REVS, '-|', qw(git rev-list --no-merges), @args)
 	    or die;
 	while (<REVS>) {
 		chomp;
@@ -52,12 +52,45 @@ sub read_revs {
 	return @revs;
 }
 
+sub rebase_marker {
+	my ($topic, $stage, $in_next) = @_;
+	my @not_in_topic = read_revs_short('^master', "^$topic", "$stage");
+
+	# @$in_next is what is in $stage but not in $base.
+	# @not_in_topic excludes what came from $topic from @$in_next.
+	# $topic can be rebased if these two set matches, because
+	# no commits in $topic has been merged to $stage yet.
+	if (@not_in_topic != @$in_next) {
+		# we cannot rebase it anymore
+		return ' ';
+	}
+	if (read_revs_short('master', "^$topic")) {
+		# there is something that is in master but not in topic.
+		return '^';
+	}
+	# topic is up to date.
+	return '*';
+}
+
+sub describe_topic {
+	my ($topic) = @_;
+	open(CONF, '-|', qw(git repo-config --get),
+		"branch.$topic.description")
+		or die;
+	my $it = join('',<CONF>);
+	close(CONF);
+	chomp($it);
+	if ($it) {
+		wrap_print("  $it");
+	}
+}
+
 sub wrap_print {
-	my ($prefix, $string) = @_;
+	my ($string) = @_;
 	format STDOUT =
-  @ ^<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<
-	$prefix, $string
-  ~~^<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<
+~^<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<
+	$string
+ ~~^<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<
 	$string
 .
 	write;
@@ -69,6 +102,8 @@ open(TOPIC, '-|', qw(git for-each-ref),
 	"refs/heads/$topic_pattern")
 	or die;
 
+my @in_next = read_revs_short('^master', $stage[0]);
+
 while (<TOPIC>) {
 	chomp;
 	my ($sha1, $date, $topic) = m|^([0-9a-f]{40})\s(.*?)\srefs/heads/(.+)$|
@@ -78,18 +113,21 @@ while (<TOPIC>) {
 
 	my %revs = map { $_->[0] => $_ } @revs; # fast index
 	for (my $i = 0; $i < @stage; $i++) {
-		for my $item (read_revs_short($stage[$i], $sha1)) {
+		for my $item (read_revs_short("^$stage[$i]", $sha1)) {
 			if (exists $revs{$item}) {
 				$revs{$item}[2] &= ~(1 << $i);
 			}
 		}
 	}
-	print "* $topic ($date)\n";
+
+	print '*' . rebase_marker($sha1, $stage[0], \@in_next);
+	print " $topic ($date)\n";
+	describe_topic($topic);
 	for my $item (@revs) {
 		my $mark = $item->[2];
 		if ($mark < @mark) {
 			$mark = $mark[$mark];
 		}
-		wrap_print($mark, $item->[1]);
+		wrap_print("$mark $item->[1]");
 	}
 }