fix project import with mirror enabled

app/models/project.rb

@@ -379,14 +379,6 @@ class Project < ActiveRecord::Base
   end
 
   def add_import_job
-    if repository_exists?
-      if mirror?
-        RepositoryUpdateMirrorWorker.perform_async(self.id)
-      end
-
-      return
-    end
-
     if forked?
       job_id = RepositoryForkWorker.perform_async(self.id, forked_from_project.path_with_namespace, self.namespace.path)
     else
@@ -500,7 +492,7 @@ class Project < ActiveRecord::Base
   end
 
   def update_mirror
-    return unless mirror?
+    return unless mirror? && repository_exists?
 
     return if import_in_progress?
 
@@ -508,6 +500,7 @@ class Project < ActiveRecord::Base
       import_retry
     else
       import_start
+      RepositoryUpdateMirrorWorker.perform_async(self.id)
     end
   end