Merge branch 'sh-show-pre-receive-error-merge' into 'master'

Show pre-receive error message in merge request widget

Closes gitlab-ee#10165

See merge request gitlab-org/gitlab-ce!25708

app/services/merge_requests/merge_service.rb

@@ -76,8 +76,7 @@ module MergeRequests
     def try_merge
       repository.merge(current_user, source, merge_request, commit_message)
     rescue Gitlab::Git::PreReceiveError => e
-      handle_merge_error(log_message: e.message)
-      raise_error('Something went wrong during merge pre-receive hook')
+      raise_error("Something went wrong during merge pre-receive hook: #{e.message}")
     rescue => e
       handle_merge_error(log_message: e.message)
       raise_error('Something went wrong during merge')

changelogs/unreleased/sh-show-pre-receive-error-merge.yml

+---
+title: Show pre-receive error message when merge fails
+merge_request: 25708
+author:
+type: fixed

spec/services/merge_requests/merge_service_spec.rb

@@ -244,7 +244,7 @@ describe MergeRequests::MergeService do
         service.execute(merge_request)
-        expect(merge_request.merge_error).to include('Something went wrong during merge pre-receive hook')
+        expect(merge_request.merge_error).to include("Something went wrong during merge pre-receive hook: #{error_message}")
         expect(Rails.logger).to have_received(:error).with(a_string_matching(error_message))
       end