[workspace] Running shell script
+ git checkout PR-74
error: pathspec 'PR-74' did not match any file(s) known to git.

Above is what I get when using multi-branch pipeline item pointing to a repo having a PR.
I have tried using 2.138, 2.141 and latest jenkins:jenkins docker - all fail
Thereafter, I tried with latest and 2.3.5 versions of github-branch-source - still fails with the above error.

I believe the refs are not added properly for some reason. Possibly, a bug with github-branch-source plugin for PR.