Gitpod option in blob view does not open in Gitpod

Summary

Selecting Gitpod in the single file editor (/blob) view results in an error on Gitpod.

Relates to !81902 (merged)

Steps to reproduce

• Navigate to https://gitlab.com/gitlab-org/gitlab/-/blob/master/.gitlab-ci.yml
• Select "Gitpod" from dropdown menu
• Press "Gitpod"
• Log into Gitpod if necessary
• Error

Example Project

https://gitlab.com/gitlab-org/gitlab/

What is the current bug behavior?

Gitpod shows error

Oh, no! Something went wrong! GitLab ApiError on searching for possible branches for gitlab-org/gitlab/tree/master/.gitlab-ci.yml: GitLabApiError: GitLab Request Error: The branch refname is invalid

What is the expected correct behavior?

Project loads up with selected page open

Relevant logs and/or screenshots

Option with single file	Result in Gitpod

Output of checks

Results of GitLab environment info

Expand for output related to GitLab environment info

(For installations with omnibus-gitlab package run and paste the output of:
`sudo gitlab-rake gitlab:env:info`)

(For installations from source run and paste the output of:
`sudo -u git -H bundle exec rake gitlab:env:info RAILS_ENV=production`)

Results of GitLab application Check

Expand for output related to the GitLab application check

(For installations with omnibus-gitlab package run and paste the output of:
sudo gitlab-rake gitlab:check SANITIZE=true)
(For installations from source run and paste the output of:
sudo -u git -H bundle exec rake gitlab:check RAILS_ENV=production SANITIZE=true)
(we will only investigate if the tests are passing)

Possible fixes