tag-build: sign merge commits

Author: Thynix

tag-build

@@ -116,7 +116,7 @@ if test $BRANCH != "master" && test $BRANCH != "next"; then
 	# Common case: Releasing from a branch, e.g. stable-9999, fixes
 	echo "Merging active branch $BRANCH back into master."
 	git checkout master
-	git merge --ff-only $TAG || exit 7
+	git merge -S --ff-only $TAG || exit 7
 
 	# Then offer to delete it.
 	echo "Delete branch $BRANCH? [y/N]"
@@ -131,12 +131,12 @@ if test $BRANCH != "master" && test $BRANCH != "next"; then
 
 	# Merge master into next.
 	git checkout next
-	git merge master
+	git merge -S master
 elif test $BRANCH == "next"; then
 	# Releasing from next.
 	# Merge next into master.
 	git checkout master
-	git merge next
+	git merge -S next
 fi
 
 # Push changes and end on next.