Improve error message when attempting to reopen MR and there's a new open MR for the same branch

2 files changed, 5 insertions, 1 deletions

diff --git a/app/controllers/projects/merge_requests_controller.rb b/app/controllers/projects/merge_requests_controller.rb
index d521db79f85..9781d159540 100644
--- a/app/controllers/projects/merge_requests_controller.rb
+++ b/app/controllers/projects/merge_requests_controller.rb
@@ -122,6 +122,10 @@ class Projects::MergeRequestsController < Projects::MergeRequests::ApplicationCo
 
     respond_to do |format|
       format.html do
+        if merge_request_params[:state_event] && @merge_request.errors.any?
+          flash[:alert] = @merge_request.errors.values.flatten.to_sentence
+        end
+
         if @merge_request.valid?
           redirect_to([@merge_request.target_project.namespace.becomes(Namespace), @merge_request.target_project, @merge_request])
         else
diff --git a/app/models/merge_request.rb b/app/models/merge_request.rb
index d0811a715bc..b50cfa639e0 100644
--- a/app/models/merge_request.rb
+++ b/app/models/merge_request.rb
@@ -547,7 +547,7 @@ class MergeRequest < ActiveRecord::Base
       similar_mrs = similar_mrs.where('id not in (?)', self.id) if self.id
       if similar_mrs.any?
         errors.add :validate_branches,
-                   "Cannot Create: This merge request already exists: #{similar_mrs.pluck(:title)}"
+                   "Cannot open this Merge Request because another open Merge Request already exists for this source branch: #{similar_mrs.first.title}"
       end
     end
   end