osmo-release.sh: Use set -e before applying changes to prepare release

Change-Id: I783c3645537258a75ae6f5a684489d629b852188
diff --git a/osmo-release.sh b/osmo-release.sh
index 4450436..916af84 100755
--- a/osmo-release.sh
+++ b/osmo-release.sh
@@ -162,6 +162,7 @@
 	exit 0
 fi
 
+set -e
 if [ -f "TODO-RELEASE" ]; then
 	grep '#' TODO-RELEASE > TODO-RELEASE.clean
 	mv TODO-RELEASE.clean TODO-RELEASE