Frequent rebase error: Another rebase is already in progress

Summary

A customer is frequently seeing "Another rebase is already in progress" errors when rebasing merge requests.

Steps to reproduce

  1. I just created an MR today, and then hit the rebase button
  2. I see "rebase in progress"
  3. Spins (for a while)
  4. I see "Merge failed: Rebase task canceled: Another rebase is already in progress. Please try again."
  5. I see "Fast-forward merge is not possible. Rebase the source branch onto the target branch or merge target branch into source branch to allow this merge request to be merged."

This error doesn’t make sense, as it’s not impacting other files that were changed?

Example Project

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What is the current bug behavior?

(What actually happens)

What is the expected correct behavior?

Rebase should have succeeded.

Relevant logs and/or screenshots

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Output of checks

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Results of GitLab environment info

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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

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(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

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