[DRE-maint] Bug#964097: gitlab: "git push" fails with a stacktrace in gitlab code due to outdated ruby version

[Maximilian Stein]

Source: gitlab
Version: 13.1.1-1+fto10+1
Severity: important

Dear Maintainer,

After upgrade to above mentioned version, `git push`es started to fail
on my repositories (while `git pull`s continued working).
Investigating the issue I noticed that there were stack traces logged
into /var/log/gitlab/exceptions_json.log every time I tried pushing.

The stack traces pointed to lib/gitlab/gl_repository/identifier.rb:52,
where apparently a string is converted to an integer. The excetion
message reads "wrong number of arguments (given 3, expected 1..2)".
According to the documentation of ruby, there were only two arguments
to `Integer` in 2.5.1
(https://ruby-doc.org/core-2.5.1/Kernel.html#method-i-Integer), while
there was a third one added later (e.g. present in 2.7). However,
since my system is based on buster, I have ruby 2.5.1 installed.

I could work around my issue by removing the third `exception: false`
parameter to `Integer` in
/usr/share/gitlab/lib/gitlab/gl_repository/identifier.rb:52.

Since there is no newer ruby version available in backports or
fasttrack, I'd prefer to stick to the stable version. What solution
can you recommend? Do you need any more information?

Relevant package versions:

gitlab: 13.1.1-1+fto10+1
gitlab-common: 13.1.0+dfsg-1~bpo10+1
gitaly: 13.1.0+dfsg-1~bpo10+1
gitlab-shell: 13.3.0+debian-1~bpo10+1

Best,
Maximilian