Error when re-running CI on PR: reference is not a tree

[lovasoa]

Hello,
When re-running failed tests on a PR in sql-js/sql.js#388 , actions/checkout encountered the following error :

 git checkout --progress --force 13088203ce13456b5da57c24664c2ff6f174dc2a
##[error]fatal: reference is not a tree: 13088203ce13456b5da57c24664c2ff6f174dc2a
##[error]Git checkout failed with exit code: 128
##[error]Exit code 1 returned from process: file name '/home/runner/runners/2.169.0/bin/Runner.PluginHost', arguments 'action "GitHub.Runner.Plugins.Repository.v1_0.CheckoutTask, Runner.Plugins"'.

[ericsciple]

Are you using actions/checkout@v2 or actions/checkout@v1? This sounds like a race condition that was fixed in v2.

[lovasoa]

This error happened with actions/checkout@v1, indeed.

[ericsciple]

Yep this is fixed in v2. V2 fetches a specific SHA.

Whereas V1 fetched the ref (refs/pull/#/merge) and then tried to checkout the SHA. It's a race condition. A new push to the PR, causes the ref to point to a new merge commit. So the old SHA isn't in the history anymore when refs/pull/#/merge is fetched.

I'm going to add a troubleshooting doc. Will add a section for this issue.

[ericsciple]

It would also be great if the error were more actionable.

[ericsciple]

duplicate of this issue: #23

[TomasHubelbauer]

FWIW the linked duplicate is closed, but this issue still reproduces in some cases, so it is good to have an open issue around.