Dangling Commits cause bad PR checkouts

[jeffreye-intel]

Related to #299 and #237, we've found that a dangling/unreachable commit following a force push is now being used as the merge commit on every PR in the repository. We've tested several prior versions of actions/checkout and have reproduced the result. This run occurs in a private repository, so I can't share the log and commit info unfortunately.

[jeffreye-intel]

Found this occurs when the runner side git repo ends up in the detached head state. When in that state, the action seems to be unable to find the appropriate commit, but "git checkout " in the repo does properly find the commit.

[thastings3]

We are hitting the same symptom as well - and possibly due to the same cause. I can see one dangling commit but unsure how to get the runner side git repo back into a good state

[thastings3]

In converting our build step from:

on: 
  pull_request:
    branches: 
      - main
  push:
    branches:
      - main

to:

on: push

We were then able to successfully snag the correct SHA for our staging level builds. So maybe I was just seeing a similar symptom but a totally different cause

[marcandrews]

I created a branch from an older commit and added commits to this branch and I experiencing this build issue as well. @thastings3 solution seems to have resolved it for me.