testing release-to-github pipeline

wercker.yml

@@ -110,7 +110,7 @@ release-to-github: # would be run on release branch
         GITHUB_ORIGIN=https://yuki-takei:$GITHUB_TOKEN@$WERCKER_GIT_DOMAIN/$WERCKER_GIT_OWNER/$WERCKER_GIT_REPOSITORY.git
         git remote rm origin
         git remote add origin $GITHUB_ORIGIN
-        git push origin
+        git push origin HEAD:release
 
     - github-create-release:
       token: $GITHUB_TOKEN