Registry/Mattermost and HTTPS-Redirect: Let's Encrypt validation fails

Summary

When configuring registry_nginx['redirect_http_to_https'] = true in gitlab.rb, the Let's Encrypt validation for the registry and the mattermost domain name fails due to a 301 redirect to gitlab When the redirect is not active, the default gitlab nginx server is used, thus the validation is successful.

Steps to reproduce

Have gitlab.rb to include a Redirect from HTTP to HTTPS for Gitlab, Mattermost and the Registry
Enable Let's Encrypt handling in gitlab

What is the current bug behavior?

Let's Encrypt tries to validate three domains for one certificate: gitlab itself, registry and mattermost
Registry and Mattermost can't be validated, as Let's Encrypt encounters a 301 redirect
thus, the certificate can never be created

What is the expected correct behavior?

if Lets Encrypt is enabled, the nginx configuration for Mattermost and the Registry will also include an Alias to the well-known directory, so validation can happen successfully.
This is already the case for nginx-gitlab-http.conf.erb
nginx-gitlab-registry-http.conf.erb is missing the Alias
as well as nginx-gitlab-mattermost-http.conf.erb

Relevant logs

52.29.173.72 - - [19/Oct/2018:16:59:04 +0000] "GET /.well-known/acme-challenge/9dfGptP5ICFj-IHtCb8-hPMoecywyqFwnR4bdTXGdvc HTTP/1.1" 301 178 "" "Mozilla/5.0 (compatible; Let's Encrypt validation server; +https://www.letsencrypt.org)"
13.58.30.69 - - [19/Oct/2018:16:59:04 +0000] "GET /.well-known/acme-challenge/9dfGptP5ICFj-IHtCb8-hPMoecywyqFwnR4bdTXGdvc HTTP/1.1" 301 178 "" "Mozilla/5.0 (compatible; Let's Encrypt validation server; +https://www.letsencrypt.org)"
34.213.106.112 - - [19/Oct/2018:16:59:05 +0000] "GET /.well-known/acme-challenge/9dfGptP5ICFj-IHtCb8-hPMoecywyqFwnR4bdTXGdvc HTTP/1.1" 301 178 "" "Mozilla/5.0 (compatible; Let's Encrypt validation server; +https://www.letsencrypt.org)"
66.133.109.36 - - [19/Oct/2018:16:59:05 +0000] "GET /.well-known/acme-challenge/9dfGptP5ICFj-IHtCb8-hPMoecywyqFwnR4bdTXGdvc HTTP/1.1" 301 178 "" "Mozilla/5.0 (compatible; Let's Encrypt validation server; +https://www.letsencrypt.org)"

Details of package version

Provide the package version installation details

ii  gitlab-ce                                            11.3.6-ce.0                     amd64                           GitLab Community Edition (including NGINX, Postgres, Redis)
un  gitlab-ci-multi-runner                                                                                   (no description available)
un  gitlab-ci-multi-runner-beta                                                                              (no description available)
un  gitlab-ee                                                                                                (no description available)
ii  gitlab-runner                                        11.3.1                          amd64                           GitLab Runner
un  gitlab-runner-beta                                                                                       (no description available)

Environment details

Operating System: Debian Stretch
Installation Target, remove incorrect values:
- Bare Metal Machine
Installation Type, remove incorrect values:
- Other: Omnibus since version 8 or so
Is there any other software running on the machine: no, just gitlab-omnibus with gitlab-runner (and docker)
single node installation?
Resources
- CPU: 4 cores
- Memory total: 32G

Configuration details

Provide the relevant sections of `/etc/gitlab/gitlab.rb`

external_url 'https://git.example.com'
nginx['redirect_http_to_https'] = true
letsencrypt['enable'] = true
registry['registry_enabled'] = true
mattermost_external_url 'https://team.example.com'
mattermost['enable'] = true
mattermost_nginx['port'] = 443
mattermost_nginx['redirect_http_to_https'] = true
registry_external_url 'https://registry.example.com'
registry_nginx['port'] = 443
registry_nginx['redirect_http_to_https'] = true