Merge branch 'fix/gb/add-missing-foreign-key-to-database-schema' into 'master'

Add missing pipeline build foreign key to the schema

See merge request gitlab-org/gitlab-ce!18846

db/schema.rb

@@ -2148,6 +2148,7 @@ ActiveRecord::Schema.define(version: 20180508135515) do
   add_foreign_key "ci_build_trace_sections", "ci_builds", column: "build_id", name: "fk_4ebe41f502", on_delete: :cascade
   add_foreign_key "ci_build_trace_sections", "projects", on_delete: :cascade
   add_foreign_key "ci_builds", "ci_pipelines", column: "auto_canceled_by_id", name: "fk_a2141b1522", on_delete: :nullify
+  add_foreign_key "ci_builds", "ci_pipelines", column: "commit_id", name: "fk_d3130c9a7f", on_delete: :cascade
   add_foreign_key "ci_builds", "ci_stages", column: "stage_id", name: "fk_3a9eaa254d", on_delete: :cascade
   add_foreign_key "ci_builds", "projects", name: "fk_befce0568a", on_delete: :cascade
   add_foreign_key "ci_builds_metadata", "ci_builds", column: "build_id", on_delete: :cascade