jira integration not working since upgrade to 12.6.2

Summary

(Summarize the bug encountered concisely)

We have upgraded our Gitlab instance to 12.6.2-ee and since then the JIRA integration is not working anymore, so that currently no comments in jira are created by the Gitlab user.

Steps to reproduce

• Enable JIRA Integration in Project
• Enter URL User&Password and ensure that all checkboxes are selected at least the "Commit" trigger.
• Make changes to the project and push it with an commit message like TICKET-1 example message

Example Project

(If possible, please create an example project here on GitLab.com that exhibits the problematic behavior, and link to it here in the bug report)

(If you are using an older version of GitLab, this will also determine whether the bug is fixed in a more recent version)

What is the current bug behavior?

Currently no comments in JIRA are created by the Gitlab JIRA Integration.

What is the expected correct behavior?

Instead we should see commits like these in JIRA.

sbaygithub mentioned this issue in a commit of testgroup/myrepo: 'TICKET-1 example message'

Relevant logs and/or screenshots

(Paste any relevant logs - please use code blocks (```) to format console output, logs, and code as it's tough to read otherwise.)

{"severity":"ERROR","time":"2020-01-08T07:42:10.391Z","correlation_id":"0ad01b15-d3fa-42e4-ad99-8fe38622fab5","service_class":"JiraService","project_id":74,"project_path":"testgroup/myrepo","message":"Error sending message","client_url":"https://my-jira.url","error":""}

Output of checks

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

Results of GitLab environment info

Expand for output related to GitLab environment info

System information
System:		Debian 9.11
Proxy:		no
Current User:	git
Using RVM:	no
Ruby Version:	2.6.3p62
Gem Version:	2.7.9
Bundler Version:1.17.3
Rake Version:	12.3.3
Redis Version:	3.2.12
Git Version:	2.24.1
Sidekiq Version:5.2.7
Go Version:	unknown
GitLab information
Version:	12.6.2-ee
Revision:	cf39803b81f
Directory:	/opt/gitlab/embedded/service/gitlab-rails
DB Adapter:	PostgreSQL
DB Version:	10.9
URL:		https://my-jira.url
HTTP Clone URL:	https://my-jira.url/some-group/some-project.git
SSH Clone URL:	git@https://my-jira.url:some-group/some-project.git
Elasticsearch:	no
Geo:		no
Using LDAP:	yes
Using Omniauth:	yes
Omniauth Providers:
GitLab Shell
Version:	10.3.0
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

$ gitlab-rake gitlab:check SANITIZE=true
Checking GitLab subtasks ...
Checking GitLab Shell ...
GitLab Shell: ... GitLab Shell version >= 10.3.0 ? ... OK (10.3.0)
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: ... Server: ldapmain
LDAP authentication... Success
LDAP users with access to your GitLab server (only showing the first 100 results)
User output sanitized. Found 100 users of 100 limit.
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: ...
3/1 ... yes
3/2 ... yes
3/3 ... yes
3/4 ... yes
3/5 ... yes
3/6 ... yes
3/7 ... yes
3/8 ... yes
3/9 ... yes
3/10 ... yes
3/11 ... yes
3/12 ... yes
3/13 ... yes
3/14 ... yes
3/15 ... yes
3/16 ... yes
3/17 ... yes
3/18 ... yes
3/19 ... yes
3/20 ... yes
3/22 ... yes
3/23 ... yes
3/24 ... yes
3/25 ... yes
3/26 ... yes
3/27 ... yes
3/29 ... yes
3/30 ... yes
3/31 ... yes
4/33 ... yes
4/34 ... yes
4/35 ... yes
4/36 ... yes
4/37 ... yes
4/39 ... yes
4/40 ... yes
4/41 ... yes
4/42 ... yes
4/43 ... yes
3/46 ... yes
8/59 ... yes
8/60 ... yes
8/61 ... yes
8/62 ... yes
8/63 ... yes
4/67 ... yes
11/70 ... yes
4/73 ... yes
3/74 ... yes
4/75 ... yes
4/79 ... yes
2/83 ... yes
4/85 ... yes
3/86 ... yes
4/87 ... yes
3/88 ... yes
4/89 ... yes
4/90 ... yes
4/91 ... yes
3/94 ... yes
3/95 ... yes
3/96 ... yes
4/97 ... yes
4/98 ... yes
3/100 ... yes
4/104 ... yes
4/105 ... yes
3/106 ... yes
4/107 ... yes
3/108 ... yes
4/110 ... yes
4/111 ... yes
4/112 ... yes
4/113 ... yes
4/114 ... yes
4/115 ... yes
4/116 ... yes
13/117 ... yes
13/118 ... yes
4/119 ... yes
13/120 ... yes
3/121 ... yes
3/122 ... yes
4/123 ... yes
Redis version >= 2.8.0? ... yes
Ruby version >= 2.5.3 ? ... yes (2.6.3)
Git version >= 2.22.0 ? ... yes (2.24.1)
Git user has default SSH configuration? ... yes
Active users: ... 4
Is authorized keys file accessible? ... yes
Elasticsearch version 5.6 - 6.x? ... skipped (elasticsearch is disabled)
Checking GitLab App ... Finished
Checking GitLab subtasks ... Finished

Possible fixes

(If you can, link to the line of code that might be responsible for the problem)