Revert "Cleanup after adding MR diff's commit_count"

This reverts commit 0b7d108514.

app/models/merge_request_diff.rb

@@ -197,6 +197,10 @@ class MergeRequestDiff < ActiveRecord::Base
     CompareService.new(project, head_commit_sha).execute(project, sha, straight: true)
   end
 
+  def commits_count
+    super || merge_request_diff_commits.size
+  end
+
   private
 
   def create_merge_request_diff_files(diffs)

db/migrate/20180304204842_clean_commits_count_migration.rb

@@ -1,14 +0,0 @@
-class CleanCommitsCountMigration < ActiveRecord::Migration
-  include Gitlab::Database::MigrationHelpers
-
-  DOWNTIME = false
-
-  disable_ddl_transaction!
-
-  def up
-    Gitlab::BackgroundMigration.steal('AddMergeRequestDiffCommitsCount')
-  end
-
-  def down
-  end
-end

doc/user/project/settings/import_export.md

@@ -31,8 +31,7 @@ with all their related data and be moved into a new GitLab instance.
 
 | GitLab version   | Import/Export version |
 | ---------------- | --------------------- |
-| 10.6 to current  | 0.2.3                 |
-| 10.4             | 0.2.2                 |
+| 10.4 to current  | 0.2.2                 |
 | 10.3             | 0.2.1                 |
 | 10.0             | 0.2.0                 |
 | 9.4.0            | 0.1.8                 |

lib/gitlab/import_export.rb

@@ -3,7 +3,7 @@ module Gitlab
     extend self
 
     # For every version update, the version history in import_export.md has to be kept up to date.
-    VERSION = '0.2.3'.freeze
+    VERSION = '0.2.2'.freeze
     FILENAME_LIMIT = 50
 
     def export_path(relative_path:)