Markdown Wiki links to other pages/files stop working on Upgrade to 13.0.3

Summary

I have upgraded today my gitlab-ce to Version 13.0.3 (In Ubuntu 18.04 - 64-bit). All of my markdown wiki links that do not use full url now fail with error 404.

Note that NO other changes (other than the update) were made, and the page links were working perfectly.

Please share any ideas on were to problem source might be.

(Thanks in Advance.)

Steps to reproduce

A simple creation of a new project wiki.
Example of a markdown page:

home page

[This is a new bas-folder page](new-base-page)

[This is a new nested page](nested/new-page)

Example Project

GitLab.com does not exhibits the problematic behavior as it runs different version.

What is the current bug behavior?

The problem is that the full path ‘rendering’ of the markdown page link is wrong (Please not the duplication of gitlab/):

Example for [This is a new bas-folder page](new-base-page) above:

  • Rendered url: <MyServer>/gitlab/gitlab/acombo/test-project/-/wikis/new-base-page
  • Actual url: <MyServer>/gitlab/acombo/test-project/-/wikis/new-base-page

What is the expected correct behavior?

The rendering of [This is a new bas-folder page](new-base-page) should be <MyServer>/gitlab/acombo/test-project/-/wikis/new-base-page

Results of GitLab environment info

Expand for output related to GitLab environment info
System information
System:		Ubuntu 18.04
Current User:	git
Using RVM:	no
Ruby Version:	2.6.6p146
Gem Version:	2.7.10
Bundler Version:1.17.3
Rake Version:	12.3.3
Redis Version:	5.0.9
Git Version:	2.26.2
Sidekiq Version:5.2.7
Go Version:	unknown

GitLab information
Version:	13.0.3
Revision:	e2397fc2acb
Directory:	/opt/gitlab/embedded/service/gitlab-rails
DB Adapter:	PostgreSQL
DB Version:	11.7
URL:		https://atena.ddns.net/gitlab
HTTP Clone URL:	https://atena.ddns.net/gitlab/some-group/some-project.git
SSH Clone URL:	ssh://git@atena.ddns.net:4442/some-group/some-project.git
Using LDAP:	no
Using Omniauth:	yes
Omniauth Providers: bitbucket

GitLab Shell
Version:	13.2.0
Repository storage paths:
- default: 	/var/opt/gitlab/git-data/repositories
GitLab Shell path:		/opt/gitlab/embedded/service/gitlab-shell
Git:		/opt/gitlab/embedded/bin/git


Results of GitLab application Check

Expand for output related to the GitLab application check

Checking GitLab subtasks …

Checking GitLab Shell …

GitLab Shell: … GitLab Shell version >= 13.2.0 ? … OK (13.2.0)
Running /opt/gitlab/embedded/service/gitlab-shell/bin/check
Internal API available: OK
Redis available via internal API: OK
gitlab-shell self-check successful

Checking GitLab Shell … Finished

Checking Gitaly …

Gitaly: … default … OK

Checking Gitaly … Finished

Checking Sidekiq …

Sidekiq: … Running? … yes
Number of Sidekiq processes … 1

Checking Sidekiq … Finished

Checking Incoming Email …

Incoming Email: … Reply by email is disabled in config/gitlab.yml

Checking Incoming Email … Finished

Checking LDAP …

LDAP: … LDAP is disabled in config/gitlab.yml

Checking LDAP … Finished

Checking GitLab App …

Git configured correctly? … yes
Database config exists? … yes
All migrations up? … yes
Database contains orphaned GroupMembers? … no
GitLab config exists? … yes
GitLab config up to date? … yes
Log directory writable? … yes
Tmp directory writable? … yes
Uploads directory exists? … yes
Uploads directory has correct permissions? … yes
Uploads directory tmp has correct permissions? … yes
Init script exists? … skipped (omnibus-gitlab has no init script)
Init script up-to-date? … skipped (omnibus-gitlab has no init script)
Projects have namespace: …
4/1 … yes
2/3 … yes
4/4 … yes
4/5 … yes
5/6 … yes
7/7 … yes
7/8 … yes
9/9 … yes
10/10 … yes
10/11 … yes
2/13 … yes
12/14 … yes
8/15 … yes
11/16 … yes
14/17 … yes
11/18 … yes
10/19 … yes
16/21 … yes
16/22 … yes
16/23 … yes
17/24 … yes
18/25 … yes
20/26 … yes
21/27 … yes
5/29 … yes
11/30 … yes
22/31 … yes
22/32 … yes
18/33 … yes
2/34 … yes
Redis version >= 4.0.0? … yes
Ruby version >= 2.5.3 ? … yes (2.6.6)
Git version >= 2.22.0 ? … yes (2.26.2)
Git user has default SSH configuration? … yes
Active users: … 3
Is authorized keys file accessible? … yes
GitLab configured to store new projects in hashed storage? … yes
All projects are in hashed storage? … yes

Checking GitLab App … Finished

Checking GitLab subtasks … Finished

I am experiencing the same issue.
Running Gitlab 13.0.5
Installed under https://<domain>/gitlab
Wiki Markdown links are being rendered as https://<domain>/gitlab/gitlab/.... and so all wiki links are broken (unless using absolute URL)