Fix fallback logic for automatic MR title assignment

app/services/merge_requests/build_service.rb

@@ -162,7 +162,7 @@ module MergeRequests
     def assign_title_from_issue
       return unless issue
 
-      merge_request.title = "Resolve \"#{issue.title}\"" if issue.is_a?(Issue)
+      merge_request.title ||= "Resolve \"#{issue.title}\"" if issue.is_a?(Issue)
 
       return if merge_request.title.present?
 

changelogs/unreleased/fix-mr-title-fallback-logic.yml

+---
+title: Fix fallback logic for automatic MR title assignment 
+merge_request: 20930
+author: Franz Liedke
+type: fixed