mirror: trigger additional push webhook on new branch (#5508)
mirror: trigger additional push webhook on new branch (#5508)

This commit fixes issue #5473 and makes a new branch behave like a
      push event and trigger the appropriate webhook.
gogits/gogs,gogits/gogs,mukaiu/gogs,chriswatt/gogs,mukaiu/gogs,chriswatt/gogs,gogits/gogs,mukaiu/gogs,chriswatt/gogs