Cleanup after adding MR diff's commit_count

* processes any pending records which are not migrated yet
* bumps import_export version because of new commits_count attribute
* removes commits_count fallback method

app/models/merge_request_diff.rb

@@ -197,10 +197,6 @@ 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

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

db/schema.rb

@@ -11,7 +11,7 @@
 #
 # It's strongly recommended that you check this file into your version control system.
 
-ActiveRecord::Schema.define(version: 20180301084653) do
+ActiveRecord::Schema.define(version: 20180304204842) do
 
   # These are extensions that must be enabled in order to support this database
   enable_extension "plpgsql"

doc/user/project/settings/import_export.md

@@ -31,7 +31,8 @@ with all their related data and be moved into a new GitLab instance.
 
 | GitLab version   | Import/Export version |
 | ---------------- | --------------------- |
-| 10.4 to current  | 0.2.2                 |
+| 10.6 to current  | 0.2.3                 |
+| 10.4             | 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 = '0.2.2'.freeze
+    VERSION = '0.2.3'.freeze
     FILENAME_LIMIT = 50
 
     def export_path(relative_path:)