git pull, git clone, hanging in GitLab-CE-12.1.6 docker image

Summary

git pull fails.

Steps to reproduce

Upgraded to the latest docker ce image on a working GitLab installation,

"git pull" is now hanging.

GitLab Community Edition, Up-To-Date: v12.1.6

docker images
REPOSITORY          TAG                 IMAGE ID            CREATED             SIZE
gitlab/gitlab-ce    latest              eb85f9e7e4b4        4 days ago          1.838 GB

https://gitlab.com/gitlab-org/gitlab-ce/-/tags/v12.1.6

Results of GitLab environment info

root@a0dd9ba0e297:/# gitlab-rake gitlab:env:info

System information
System:
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:    2.21.0
Sidekiq Version:5.2.7
Go Version:     unknown

GitLab information
Version:        12.1.6
Revision:       4016bcac51d
Directory:      /opt/gitlab/embedded/service/gitlab-rails
DB Adapter:     PostgreSQL
DB Version:     10.7
URL:            https://gitlab.sylvan.com
HTTP Clone URL: https://gitlab.sylvan.com/some-group/some-project.git
SSH Clone URL:  git@gitlab.sylvan.com:some-group/some-project.git
Using LDAP:     no
Using Omniauth: yes
Omniauth Providers: 

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

root@a0dd9ba0e297:/# gitlab-rake gitlab:check SANITIZE=true
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: ... 
2/1 ... yes
2/2 ... yes
2/3 ... yes
2/4 ... yes
15/5 ... yes
15/6 ... yes
2/7 ... yes
2/8 ... yes
2/9 ... yes
2/10 ... yes
2/11 ... yes
Redis version >= 2.8.0? ... yes
Ruby version >= 2.5.3 ? ... yes (2.6.3)
Git version >= 2.21.0 ? ... yes (2.21.0)
Git user has default SSH configuration? ... yes
Active users: ... 6

Checking GitLab App ... Finished


Checking GitLab subtasks ... Finished

root@a0dd9ba0e297:/# gitlab-rake gitlab:check SANITIZE=true
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: ... 
2/1 ... yes
2/2 ... yes
2/3 ... yes
2/4 ... yes
15/5 ... yes
15/6 ... yes
2/7 ... yes
2/8 ... yes
2/9 ... yes
2/10 ... yes
2/11 ... yes
Redis version >= 2.8.0? ... yes
Ruby version >= 2.5.3 ? ... yes (2.6.3)
Git version >= 2.21.0 ? ... yes (2.21.0)
Git user has default SSH configuration? ... yes
Active users: ... 6

Checking GitLab App ... Finished


Checking GitLab subtasks ... Finished