Drop-down menus not working after upgrade from 8.13 to 8.17

Summary

After an upgrade on Debian Jessie, from Gitlab CE v8.13 to 8.17, the drop-down menus on the web interface do not work anymore.

Steps to reproduce

Click on a button that is supposed to show a menu, for example the hamburger on the top-right. Nothing happens visually. The URL changes from my/project/url to my/project/url#.

What is the current bug behavior?

No menu is shown.

What is the expected correct behavior?

A menu should be shown.

Relevant logs and/or screenshots

I don't know what logs are relevant.

Output of checks

(If you are reporting a bug on GitLab.com, write: This bug happens on GitLab.com)

Results of GitLab environment info

Result of gitlab-rake gitlab:env:info:

System information
System:         Debian 8.7
Current User:   git
Using RVM:      no
Ruby Version:   2.3.3p222
Gem Version:    2.6.6
Bundler Version:1.13.7
Rake Version:   10.5.0
Redis Version:  3.2.5
Sidekiq Version:4.2.7

GitLab information
Version:        8.17.0
Revision:       77254ab
Directory:      /opt/gitlab/embedded/service/gitlab-rails
DB Adapter:     postgresql
URL:            https://source.example.com
HTTP Clone URL: https://source.example.com/some-group/some-project.git
SSH Clone URL:  git@source.example.com:some-group/some-project.git
Using LDAP:     no
Using Omniauth: no

GitLab Shell
Version:        4.1.1
Repository storage paths:
- default:      /var/opt/gitlab/git-data/repositories
Hooks:          /opt/gitlab/embedded/service/gitlab-shell/hooks/
Git:            /opt/gitlab/embedded/bin/git

Results of GitLab application Check

Result of gitlab-rake gitlab:check SANITIZE=true:

Checking GitLab Shell ...

GitLab Shell version >= 4.1.1 ? ... OK (4.1.1)
Repo base directory exists?
default... yes
Repo storage directories are symlinks?
default... no
Repo paths owned by git:git?
default... yes
Repo paths access is drwxrws---?
default... yes
hooks directories in repos are links: ... 
3/1 ... ok
4/3 ... ok
4/8 ... ok
3/9 ... ok
3/10 ... ok
3/11 ... ok
3/12 ... ok
4/13 ... ok
2/15 ... repository is empty
Running /opt/gitlab/embedded/service/gitlab-shell/bin/check
Check GitLab API access: OK
Access to /var/opt/gitlab/.ssh/authorized_keys: OK
Send ping to redis server: OK
gitlab-shell self-check successful

Checking GitLab Shell ... Finished

Checking Sidekiq ...

Running? ... yes
Number of Sidekiq processes ... 1

Checking Sidekiq ... Finished

Checking Reply by email ...

Reply by email is disabled in config/gitlab.yml

Checking Reply by email ... Finished

Checking LDAP ...

LDAP is disabled in config/gitlab.yml

Checking LDAP ... Finished

Checking GitLab ...

Git configured with autocrlf=input? ... yes
Database config exists? ... yes
All migrations up? ... yes
Database contains orphaned GroupMembers? ... no
GitLab config exists? ... yes
GitLab config outdated? ... no
Log directory writable? ... yes
Tmp directory writable? ... yes
Uploads directory setup correctly? ... skipped (no tmp uploads folder yet)
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: ... 
3/1 ... yes
4/3 ... yes
4/8 ... yes
3/9 ... yes
3/10 ... yes
3/11 ... yes
3/12 ... yes
4/13 ... yes
2/15 ... yes
Redis version >= 2.8.0? ... yes
Ruby version >= 2.1.0 ? ... yes (2.3.3)
Your git bin path is "/opt/gitlab/embedded/bin/git"
Git version >= 2.7.3 ? ... yes (2.10.2)
Active users: 2

Checking GitLab ... Finished