Add extra logging to githost.log when rebasing

app/services/merge_requests/rebase_service.rb

@@ -18,10 +18,18 @@ module MergeRequests
         return false
       end
+      log_prefix = "#{self.class.name} info (#{merge_request.to_reference(full: true)}):"
+
+      Gitlab::GitLogger.info("#{log_prefix} rebase started")
+
       rebase_sha = repository.rebase(current_user, merge_request)
+      Gitlab::GitLogger.info("#{log_prefix} rebased to #{rebase_sha}")
+
       merge_request.update_attributes(rebase_commit_sha: rebase_sha)
+      Gitlab::GitLogger.info("#{log_prefix} rebase SHA saved: #{rebase_sha}")
+
       true
     rescue => e
       log_error(REBASE_ERROR, save_message_on_model: true)

changelogs/unreleased/add-more-rebase-logging.yml

+---
+title: Add more detailed logging to githost.log when rebasing
+merge_request:
+author:
+type: other