Don't delete a branch involved in an open merge request in "Delete all merged branches" servicesh-issue-29247-fix

Customers were surprised by the previous behavior, which destroyed branches
even though an open merge request existed for it.

Closes #29427

1 files changed, 11 insertions, 0 deletions

diff --git a/app/services/delete_merged_branches_service.rb b/app/services/delete_merged_branches_service.rb
index 1b5623baebe..3b611588466 100644
--- a/app/services/delete_merged_branches_service.rb
+++ b/app/services/delete_merged_branches_service.rb
@@ -8,9 +8,20 @@ class DeleteMergedBranchesService < BaseService
 
     branches = project.repository.branch_names
     branches = branches.select { |branch| project.repository.merged_to_root_ref?(branch) }
+    # Prevent deletion of branches relevant to open merge requests
+    branches -= merge_request_branch_names
 
     branches.each do |branch|
       DeleteBranchService.new(project, current_user).execute(branch)
     end
   end
+
+  private
+
+  def merge_request_branch_names
+    # reorder(nil) is necessary for SELECT DISTINCT because default scope adds an ORDER BY
+    source_names = project.origin_merge_requests.opened.reorder(nil).uniq.pluck(:source_branch)
+    target_names = project.merge_requests.opened.reorder(nil).uniq.pluck(:target_branch)
+    (source_names + target_names).uniq
+  end
 end