[tor-bugs] #32197 [Internal Services/Service - git]: Gitlab throwing 503 when creating a Merge Request from a forked repository

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#32197: Gitlab throwing 503 when creating a Merge Request from a forked repository
-------------------------------------------------+------------------------
     Reporter:  hiro                             |      Owner:  tor-gitadm
         Type:  defect                           |     Status:  new
     Priority:  Medium                           |  Milestone:
    Component:  Internal Services/Service - git  |    Version:
     Severity:  Normal                           |   Keywords:
Actual Points:                                   |  Parent ID:
       Points:                                   |   Reviewer:
      Sponsor:                                   |
-------------------------------------------------+------------------------
 Gitlab throw a 503 error when creating a merge request from a forked
 project to the main repository.

 How to reproduce:
 - Create a fork of a project.
 - Create a MR from the fork to the main project


 Gitlab production.log shows the following:


 {{{
 Started GET
 "/hiro/bridgedb/merge_requests/new?utf8=%E2%9C%93&merge_request[source_project_id]=261&merge_request[source_branch
 ]=status-
 check&merge_request[target_project_id]=260&merge_request[target_branch]=master"
 for 185.220.101.33 at 2019-10-22 17:37:35 +0000
 Processing by Projects::MergeRequests::CreationsController#new as HTML
   Parameters: {"utf8"=>"✓", "merge_request"=>{"source_project_id"=>"261",
 "source_branch"=>"status-check", "target_project_id"=>"260",
 "target_branch"=>"master"}, "namespace_id"=>"hiro",
 "project_id"=>"bridgedb"}

 Gitlab::Git::CommandError (2:Gitlab::Git::CommandError: ):
   lib/gitlab/git/wraps_gitaly_errors.rb:13:in `rescue in
 wrapped_gitaly_errors'
   lib/gitlab/git/wraps_gitaly_errors.rb:6:in `wrapped_gitaly_errors'
   lib/gitlab/metrics/instrumentation.rb:161:in `block in
 wrapped_gitaly_errors'
   lib/gitlab/metrics/method_call.rb:36:in `measure'
   lib/gitlab/metrics/instrumentation.rb:161:in `wrapped_gitaly_errors'
   lib/gitlab/git/repository.rb:722:in `fetch_source_branch!'
   lib/gitlab/git/repository.rb:746:in `compare_source_branch'
   app/models/repository.rb:953:in `compare_source_branch'
   lib/gitlab/metrics/instrumentation.rb:161:in `block in
 compare_source_branch'
   lib/gitlab/metrics/method_call.rb:36:in `measure'
   lib/gitlab/metrics/instrumentation.rb:161:in `compare_source_branch'
   app/services/compare_service.rb:16:in `execute'
   app/services/merge_requests/build_service.rb:125:in `compare_branches'
   lib/gitlab/metrics/instrumentation.rb:161:in `block in compare_branches'
   lib/gitlab/metrics/method_call.rb:36:in `measure'
   lib/gitlab/metrics/instrumentation.rb:161:in `compare_branches'
   app/services/merge_requests/build_service.rb:43:in `execute'
   lib/gitlab/metrics/instrumentation.rb:161:in `block in execute'
   lib/gitlab/metrics/method_call.rb:36:in `measure'
   lib/gitlab/metrics/instrumentation.rb:161:in `execute'
   app/controllers/projects/merge_requests/creations_controller.rb:97:in
 `block in build_merge_request'
   lib/gitlab/gitaly_client.rb:284:in `allow_n_plus_1_calls'
   app/controllers/projects/merge_requests/creations_controller.rb:96:in
 `build_merge_request'
   lib/gitlab/session.rb:11:in `with_session'
   app/controllers/application_controller.rb:450:in `set_session_storage'
   lib/gitlab/i18n.rb:55:in `with_locale'
   lib/gitlab/i18n.rb:61:in `with_user_locale'
   app/controllers/application_controller.rb:444:in `set_locale'
   lib/gitlab/middleware/rails_queue_duration.rb:27:in `call'
   lib/gitlab/metrics/rack_middleware.rb:17:in `block in call'
   lib/gitlab/metrics/transaction.rb:57:in `run'
   lib/gitlab/metrics/rack_middleware.rb:17:in `call'
   lib/gitlab/request_profiler/middleware.rb:17:in `call'
   lib/gitlab/middleware/go.rb:20:in `call'
   lib/gitlab/etag_caching/middleware.rb:13:in `call'
   lib/gitlab/middleware/correlation_id.rb:16:in `block in call'
   lib/gitlab/middleware/correlation_id.rb:15:in `call'
   lib/gitlab/middleware/multipart.rb:117:in `call'
   lib/gitlab/middleware/read_only/controller.rb:42:in `call'
   lib/gitlab/middleware/read_only.rb:18:in `call'
   lib/gitlab/middleware/basic_health_check.rb:25:in `call'
   lib/gitlab/request_context.rb:26:in `call'
   lib/gitlab/metrics/requests_rack_middleware.rb:29:in `call'
   lib/gitlab/middleware/release_env.rb:12:in `call'

 Completed 503 Service Unavailable in 267ms (Views: 0.7ms | ActiveRecord:
 8.6ms | Elasticsearch: 0.0ms)

 }}}

--
Ticket URL: <https://trac.torproject.org/projects/tor/ticket/32197>
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