Random error 500 when pulling/pushing to repository using HTTPS

EDIT: It also happens with pulls.

Summary

Just upgraded to 12.2 and getting random 500 errors when using git and pulling/pushing to a project using HTTPS.

Steps to reproduce

Try to pull any repository using HTTPS on http://lab.shelter.moe (self-hosted gitlab) or push to one you created there.

What is the current bug behavior?

Git commands fail with a 500 error. These errors are random as, when you try pushing again, and again, it sometimes fails during the push, and sometimes the push succeeds.

See this terminal log for an example :

$ git push -u origin master
fatal: unable to access 'https://lab.shelter.moe/axelterizaki/ultrastar2ass.git/': The requested URL returned error: 500

$ git push -u origin master
fatal: unable to access 'https://lab.shelter.moe/axelterizaki/ultrastar2ass.git/': The requested URL returned error: 500

$ git push -u origin master
Counting objects: 24, done.
Delta compression using up to 4 threads.
Compressing objects: 100% (19/19), done.
Writing objects: 100% (24/24), 25.73 KiB | 0 bytes/s, done.
Total 24 (delta 1), reused 0 (delta 0)
error: RPC failed; HTTP 500 curl 22 The requested URL returned error: 500 Internal Server Error
fatal: The remote end hung up unexpectedly
fatal: The remote end hung up unexpectedly
Everything up-to-date

$ git push -u origin master
fatal: unable to access 'https://lab.shelter.moe/axelterizaki/ultrastar2ass.git/': The requested URL returned error: 500

$ git push -u origin master
fatal: unable to access 'https://lab.shelter.moe/axelterizaki/ultrastar2ass.git/': The requested URL returned error: 500

$ git push -u origin master
Counting objects: 24, done.
Delta compression using up to 4 threads.
Compressing objects: 100% (19/19), done.
Writing objects: 100% (24/24), 25.73 KiB | 0 bytes/s, done.
Total 24 (delta 1), reused 0 (delta 0)
To https://lab.shelter.moe/axelterizaki/ultrastar2ass.git
 * [new branch]      master -> master
Branch master set up to track remote branch master from origin.

What is the expected correct behavior?

It should be working all right as in 12.1.x

This happened ever since I upgraded Omnibus gitlab to 12.2 this morning.

Relevant logs and/or screenshots

I examined the production.log and here's what I found when trying a git push :

Started GET "/axelterizaki/ultrastar2ass.git/info/refs?service=git-receive-pack" for 192.168.122.1 at 2019-08-23 12:55:18 +0200
Processing by Gitlab::RequestForgeryProtection::Controller#index as */*
  Parameters: {"service"=>"git-receive-pack"}
Completed 200 OK in 0ms (ActiveRecord: 0.0ms)

Redis::CommandError (ERR value is not an integer or out of range):

lib/peek/views/redis_detailed.rb:10:in `call'
lib/gitlab/middleware/read_only/controller.rb:40: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:26:in `call'
config/initializers/fix_local_cache_middleware.rb:9:in `call'
lib/gitlab/metrics/requests_rack_middleware.rb:29:in `call'
lib/gitlab/middleware/release_env.rb:12:in `call'

Here it says it returned a 200, but my Apache frontend server returns a 500 instead :

xx.xxx.xx.xxx - - [23/Aug/2019:13:03:05 +0200] "GET /axelterizaki/ultrastar2ass.git/info/refs?service=git-receive-pack HTTP/1.1" 500 3228 "-" "git/2.19.0.windows.1"

I'm not sure what's wrong but I guess the Redis error in production.log has something to do with it.

Output of checks

See below

Results of GitLab environment info

Expand for output related to GitLab environment info

System information
System:         Ubuntu 16.04
Current User:   git
Using RVM:      no
Ruby Version:   2.6.3p62
Gem Version:    2.7.9
Bundler Version:1.17.3
Rake Version:   12.3.2
Redis Version:  3.2.12
Git Version:    2.22.0
Sidekiq Version:5.2.7
Go Version:     unknown
GitLab information
Version:        12.2.0
Revision:       1c1d47c5974
Directory:      /opt/gitlab/embedded/service/gitlab-rails
DB Adapter:     PostgreSQL
DB Version:     10.9
URL:            https://lab.shelter.moe
HTTP Clone URL: https://lab.shelter.moe/some-group/some-project.git
SSH Clone URL:  git@shelter.mahoro-net.org:some-group/some-project.git
Using LDAP:     no
Using Omniauth: yes
Omniauth Providers: gitlab, google_oauth2, twitter, github
GitLab Shell
Version:        9.3.0
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 >= 9.3.0 ? ... OK (9.3.0)
Running /opt/gitlab/embedded/service/gitlab-shell/bin/check
Check GitLab API access: OK
Redis available via internal API: OK
Access to /var/opt/gitlab/.ssh/authorized_keys: 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: ... Checking Reply by email ...
IMAP server credentials are correct? ... yes
Init.d configured correctly? ... skipped
MailRoom running? ... skipped
Checking Reply by email ... Finished
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: ...
5/2 ... yes
2/4 ... yes
1/6 ... yes
1/7 ... yes
1/8 ... yes
7/9 ... yes
19/10 ... yes
4/11 ... yes
22/12 ... yes
156/13 ... yes
15/14 ... yes
8/15 ... yes
5/18 ... yes
45/22 ... yes
156/23 ... yes
52/24 ... yes
52/25 ... yes
59/26 ... yes
155/28 ... yes
62/32 ... yes
62/33 ... yes
52/34 ... yes
155/35 ... yes
5/36 ... yes
54/40 ... yes
67/41 ... yes
67/43 ... yes
67/44 ... yes
156/45 ... yes
65/46 ... yes
66/47 ... yes
82/52 ... yes
96/55 ... yes
82/59 ... yes
8/65 ... yes
7/66 ... yes
5/67 ... yes
5/68 ... yes
82/69 ... yes
20/70 ... yes
45/71 ... yes
110/72 ... yes
82/73 ... yes
8/74 ... yes
8/75 ... yes
8/76 ... yes
156/77 ... yes
9/80 ... yes
66/81 ... yes
78/83 ... yes
1/87 ... yes
135/89 ... yes
126/90 ... yes
135/91 ... yes
135/92 ... yes
135/93 ... yes
1/98 ... yes
153/99 ... yes
155/100 ... yes
155/101 ... yes
5/102 ... yes
20/104 ... yes
8/106 ... yes
45/107 ... yes
102/109 ... yes
129/110 ... yes
5/111 ... yes
9/112 ... yes
198/113 ... yes
102/114 ... yes
198/115 ... yes
193/116 ... yes
202/117 ... yes
45/118 ... yes
135/119 ... yes
107/120 ... yes
107/121 ... yes
20/123 ... yes
5/129 ... yes
135/130 ... yes
5/131 ... yes
52/132 ... yes
1/133 ... yes
1/134 ... yes
Redis version >= 2.8.0? ... yes
Ruby version >= 2.5.3 ? ... yes (2.6.3)
Git version >= 2.22.0 ? ... yes (2.22.0)
Git user has default SSH configuration? ... yes
Active users: ... 196
Checking GitLab App ... Finished
Checking GitLab subtasks ... Finished

Possible fixes

For now my only possible workaround is to migrate back to an older version (12.1) where this didn't happen.