Merge branch 'es_fix_remove_branch' into 'master'

ES fix exception on branch removing

fixes https://gitlab.com/gitlab-org/gitlab-ee/issues/382

See merge request !259

CHANGELOG-EE

@@ -9,6 +9,7 @@ v 8.6.0 (unreleased)
   - [Elastic] Use subprocesses for ElasticSearch index jobs
   - [Elastic] More accurate as_indexed_json (More stable database indexer)
   - [Elastic] Fix: Don't index newly created system messages and awards
+  - [Elastic] Fixed exception on branch removing
 
 v 8.5.5
   - GitLab Geo: Repository synchronization between primary and secondary nodes

lib/elastic/indexer.rb

@@ -17,6 +17,8 @@ def initialize
     end
 
     def run(project_id, repo_path, from_sha = nil, to_sha = nil)
+      to_sha = nil if to_sha == Gitlab::Git::BLANK_SHA
+
       vars = @vars.merge({ 'FROM_SHA' => from_sha, 'TO_SHA' => to_sha })
 
       command = ['bin/elastic_repo_indexer', project_id.to_s, repo_path]