[DRE-maint] Bug#947754: [omv.dynamicpuzzle.ro] gitlab mattermost integration error

[David L]

Package: gitlab
Version: 12.5.4-2+fto10+1
Followup-For: Bug #947754

Another case with the error, but in this case is not for use oauth directly, nor for sentry server integration.
(Anyways, apparently Sentry it's trying to do an oauth authentication before starting process, it's the same error apparently.

This case are only tested on 12.5.4

Started GET "/oauth/authorize?scope=api&state=<mystate>&redirect_uri=https%3A%2F%2F>sentry.fqdn>%2Fextensions%2Fgitlab%2Fsetup%2F&response_type=code&client_id=<cid>" for x.x.x.x at 2020-01-01 05:32:14 +0100
Processing by Oauth::AuthorizationsController#new as HTML
  Parameters: {"scope"=>"api", "state"=>"<mystate>", "redirect_uri"=>"https://<sentry.fqdn>/extensions/gitlab/setup/", "response_type"=>"code", "client_id"=>"<cid>"}
Completed 500 Internal Server Error in 5ms (ActiveRecord: 0.5ms | Elasticsearch: 0.0ms)

NoMethodError (undefined method `mapping' for Doorkeeper::Rails::Routes:Class):

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:48: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:32:in `call'
config/initializers/fix_local_cache_middleware.rb:9:in `call'
lib/gitlab/metrics/requests_rack_middleware.rb:49:in `call'
lib/gitlab/middleware/release_env.rb:12:in `call'