Fix migrate mirror 500 bug (#8526)

models/repo.go

@@ -1430,6 +1430,7 @@ func CreateRepository(doer, u *User, opts CreateRepoOptions) (_ *Repository, err
 		IsFsckEnabled:                   !opts.IsMirror,
 		CloseIssuesViaCommitInAnyBranch: setting.Repository.DefaultCloseIssuesViaCommitsInAnyBranch,
 		Status:                          opts.Status,
+		IsEmpty:                         !opts.AutoInit,
 	}
 
 	sess := x.NewSession()