[PATCH TOPGIT] tg export: implement skipping empty patches for collapse driver

["Uwe Kleine-König" <u.kleine-koenig@pengutronix.de>]

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
---
 README       |    1 -
 tg-export.sh |   10 +++++++---
 2 files changed, 7 insertions(+), 4 deletions(-)

diff --git a/README b/README
index c19985f..8be0d17 100644
--- a/README
+++ b/README
@@ -414,7 +414,6 @@ tg export
 	TODO: Make stripping of non-essential headers configurable
 	TODO: Make stripping of [PATCH] and other prefixes configurable
 	TODO: --mbox option for other mode of operation
-	TODO: prevent exporting of empty patches by the collapse driver
 	TODO: -a option to export all branches
 	TODO: For quilt exporting, use a temporary branch and remove it when
 	      done - this would allow producing conflict-less series
diff --git a/tg-export.sh b/tg-export.sh
index afb6f95..95aa346 100644
--- a/tg-export.sh
+++ b/tg-export.sh
@@ -91,9 +91,13 @@ collapsed_commit()
 			$(for p in $parent; do echo -p $p; done))"
 	fi
 
-	(printf '%s\n\n' "$SUBJECT"; cat "$playground/^msg") |
-	git stripspace |
-	git commit-tree "$(pretty_tree "$name")" -p "$parent"
+	if branch_empty "$name"; then
+		echo "$parent";
+	else
+		(printf '%s\n\n' "$SUBJECT"; cat "$playground/^msg") |
+		git stripspace |
+		git commit-tree "$(pretty_tree "$name")" -p "$parent"
+	fi;
 
 	echo "$name" >>"$playground/^ticker"
 }
-- 
1.5.6.5