Fix label set during issue/mr creation

app/services/issues/create_service.rb

 module Issues
   class CreateService < Issues::BaseService
     def execute
-      issue = project.issues.new(params)
+      label_params = params[:label_ids]
+      issue = project.issues.new(params.except(:label_ids))
       issue.author = current_user
 
       if issue.save
+        issue.update_attributes(label_ids: label_params)
         notification_service.new_issue(issue, current_user)
         event_service.open_issue(issue, current_user)
         issue.create_cross_references!(issue.project, current_user)

app/services/merge_requests/create_service.rb

 module MergeRequests
   class CreateService < MergeRequests::BaseService
     def execute
-      merge_request = MergeRequest.new(params)
+      label_params = params[:label_ids]
+      merge_request = MergeRequest.new(params.except(:label_ids))
       merge_request.source_project = project
       merge_request.target_project ||= project
       merge_request.author = current_user
 
       if merge_request.save
+        merge_request.update_attributes(label_ids: label_params)
         event_service.open_mr(merge_request, current_user)
         notification_service.new_merge_request(merge_request, current_user)
         merge_request.create_cross_references!(merge_request.project, current_user)