When the git ref is unable to be found return broken pr (#13218)
When the git ref is unable to be found return broken pr (#13218)

Fix #13216

Signed-off-by: Andrew Thornton <6a547fdd28db89120bdd70d4af1f9ba672ccd43a@cantab.net>
go-gitea/gitea,cez81/gitea,sapk-fork/gitea,go-gitea/gitea,cez81/gitea,cez81/gitea,sapk-fork/gitea,sapk-fork/gitea,go-gitea/gitea,vdbt/gitea,vdbt/gitea,sapk-fork/gitea