Reduce number of API requests and fix merge request events

lib/gitlab/bitbucket_server_import/importer.rb

@@ -100,13 +100,21 @@ module Gitlab
         # 2. Retried import, repo is broken or not imported but +exists?+ still returns true
         project.repository.expire_content_cache if project.repository_exists?
 
-        raise RuntimeError, e.message
+        raise e.message
       end
 
       def import_pull_requests
         pull_requests = client.pull_requests(project_key, repository_slug)
         pull_requests.each do |pull_request|
           begin
+            import_bitbucket_pull_request(pull_request)
+          rescue StandardError => e
+            errors << { type: :pull_request, iid: pull_request.iid, errors: e.message, trace: e.backtrace.join("\n"), raw_response: pull_request.raw }
+          end
+        end
+      end
+
+      def import_bitbucket_pull_request(pull_request)
         restore_branches(pull_request)
 
         description = ''
@@ -139,20 +147,14 @@ module Gitlab
         attributes[:merge_commit_sha] = target_branch_sha if pull_request.merged?
         merge_request = project.merge_requests.create!(attributes)
         import_pull_request_comments(pull_request, merge_request) if merge_request.persisted?
-          rescue StandardError => e
-            errors << { type: :pull_request, iid: pull_request.iid, errors: e.message, trace: e.backtrace.join("\n"), raw_response: pull_request.raw }
-          end
-        end
       end
 
       def import_pull_request_comments(pull_request, merge_request)
-        # XXX This is inefficient since we are making multiple requests to the activities endpoint
-        merge_event = client.activities(project_key, repository_slug, pull_request.iid).find(&:merge_event?)
+        comments, other_activities = client.activities(project_key, repository_slug, pull_request.iid).partition(&:comment?)
 
+        merge_event = other_activities.find(&:merge_event?)
         import_merge_event(merge_request, merge_event) if merge_event
 
-        comments = client.activities(project_key, repository_slug, pull_request.iid).select(&:comment?)
-
         inline_comments, pr_comments = comments.partition(&:inline_comment?)
 
         import_inline_comments(inline_comments.map(&:comment), pull_request, merge_request)
@@ -162,22 +164,11 @@ module Gitlab
       def import_merge_event(merge_request, merge_event)
         committer = merge_event.committer_email
 
-        return unless committer
-
-        user_id =
-          if committer
-            find_user_id(committer)
-          else
-            User.ghost
-          end
-
-        user_id = find_user_id(committer) if committer
+        user = User.ghost
+        user ||= find_user_id(committer) if committer
         timestamp = merge_event.merge_timestamp
-
-        return unless user_id
-
-        event = Event.create(merged_by_id: user_id, merged_at: timestamp)
-        MergeRequestMetricsService.new(merge_request.metrics).merge(event)
+        metric = MergeRequest::Metrics.find_or_initialize_by(merge_request: merge_request)
+        metric.update_attributes(merged_by: user, merged_at: timestamp)
       end
 
       def import_inline_comments(inline_comments, pull_request, merge_request)