Order-dependent spec failure: spec/lib/gitlab/database/load_balancing/connection_proxy_spec.rb

Job #1538546942 failed for 2d10648b:

This can be reproduced via:

bundle exec rspec spec/lib/gitlab/database/load_balancing_spec.rb spec/lib/gitlab/database/load_balancing/connection_proxy_spec.rb

1) Gitlab::Database::LoadBalancing::ConnectionProxy.insert_all! inserts data in bulk
     Failure/Error: connection.send(...)
     ActiveRecord::StatementInvalid:
       PG::UndefinedTable: ERROR:  relation "connection_proxy_bulk_insert" does not exist
       LINE 1: SELECT COUNT(*) FROM "connection_proxy_bulk_insert" /*applic...
                                    ^
     # ./lib/gitlab/database/load_balancing/connection_proxy.rb:95:in `block in read_using_load_balancer'
     # ./lib/gitlab/database/load_balancing/load_balancer.rb:39:in `read'
     # ./lib/gitlab/database/load_balancing/connection_proxy.rb:94:in `read_using_load_balancer'
     # ./lib/gitlab/database/load_balancing/connection_proxy.rb:47:in `select_all'
     # ./spec/lib/gitlab/database/load_balancing/connection_proxy_spec.rb:104:in `block (4 levels) in <top (required)>'
     # ./spec/lib/gitlab/database/load_balancing/connection_proxy_spec.rb:99:in `block (3 levels) in <top (required)>'
     # ./spec/spec_helper.rb:392:in `block (3 levels) in <top (required)>'
     # ./spec/support/sidekiq_middleware.rb:9:in `with_sidekiq_server_middleware'
     # ./spec/spec_helper.rb:383:in `block (2 levels) in <top (required)>'
     # ./spec/spec_helper.rb:379:in `block (3 levels) in <top (required)>'
     # ./lib/gitlab/application_context.rb:31:in `with_raw_context'
     # ./spec/spec_helper.rb:379:in `block (2 levels) in <top (required)>'
     # ./spec/support/database/prevent_cross_joins.rb:81:in `block (3 levels) in <top (required)>'
     # ./spec/support/database/prevent_cross_joins.rb:52:in `with_cross_joins_prevented'
     # ./spec/support/database/prevent_cross_joins.rb:81:in `block (2 levels) in <top (required)>'
     # ------------------
     # --- Caused by: ---
     # PG::UndefinedTable:
     #   ERROR:  relation "connection_proxy_bulk_insert" does not exist
     #   LINE 1: SELECT COUNT(*) FROM "connection_proxy_bulk_insert" /*applic...
     #                                ^
     #   ./lib/gitlab/database/load_balancing/connection_proxy.rb:95:in `block in read_using_load_balancer'

It appears RequestStore is leaking a Host across specs, causing the load balancer to be used in connection_proxy_spec.rb. Using SafeRequestStore and proper use of the :request_store annotation, but this introduces other spec failures in load_balancing_spec.rb.