Merge branch '24627-fix-bad-mr-error-message' into 'master'

Fixes regression causing an error message to appear when user first enters the Merge Request form.

Closes #24627

See merge request !7599

1 files changed, 2 insertions, 2 deletions

diff --git a/app/services/merge_requests/build_service.rb b/app/services/merge_requests/build_service.rb
index f415244068b..dd0d738674e 100644
--- a/app/services/merge_requests/build_service.rb
+++ b/app/services/merge_requests/build_service.rb
@@ -48,11 +48,11 @@ module MergeRequests
       end
 
       # See if source and target branches exist
-      unless merge_request.source_project.commit(merge_request.source_branch)
+      if merge_request.source_branch.present? && !merge_request.source_project.commit(merge_request.source_branch)
         messages << "Source branch \"#{merge_request.source_branch}\" does not exist"
       end
 
-      unless merge_request.target_project.commit(merge_request.target_branch)
+      if merge_request.target_branch.present? && !merge_request.target_project.commit(merge_request.target_branch)
         messages << "Target branch \"#{merge_request.target_branch}\" does not exist"
       end