Merge branch 'sh-fix-issue-38246' into 'master'

Fix duplicate key errors in PostDeployMigrateUserExternalMailData migration

Closes #38246

See merge request gitlab-org/gitlab-ce!14460

changelogs/unreleased/sh-fix-issue-38246.yml

+---
+title: Fix duplicate key errors in PostDeployMigrateUserExternalMailData migration
+merge_request:
+author:
+type: fixed

db/migrate/20170828135939_migrate_user_external_mail_data.rb

@@ -33,7 +33,7 @@ class MigrateUserExternalMailData < ActiveRecord::Migration
           SELECT true
           FROM user_synced_attributes_metadata
           WHERE user_id = users.id
-          AND provider = users.email_provider
+          AND provider = users.email_provider OR (provider IS NULL AND users.email_provider IS NULL)
         )
         AND id BETWEEN #{start_id} AND #{end_id}
       EOF

db/post_migrate/20170828170502_post_deploy_migrate_user_external_mail_data.rb

@@ -33,7 +33,7 @@ class PostDeployMigrateUserExternalMailData < ActiveRecord::Migration
           SELECT true
           FROM user_synced_attributes_metadata
           WHERE user_id = users.id
-          AND provider = users.email_provider
+          AND provider = users.email_provider OR (provider IS NULL AND users.email_provider IS NULL)
         )
         AND id BETWEEN #{start_id} AND #{end_id}
       EOF