fix: use raw ref for PR branch to avoid confusion bw upstream and fork

[matt-codecov]

same PR as codecov/codecov-cli#237 but for the nodejs uploader

when we upload a report for CI in a PR, we associate the report with the destination repo but we take the branch name from the source repo. so if i make a PR from my fork's main branch to an upstream repo's main branch, we upload the coverage report for the upstream repo's main branch and update the coverage with junk from my un-merged PR

this PR instead will upload refs/pull/#/merge as the branch for PRs. it's slightly less nice for same-repo PRs because in order to populate coverage for your feature branches you'll need CI running on push as well as PR, but avoids invalidating coverage for projects that use a super common fork/merge workflow

docs on the environment variables used here: https://docs.github.com/en/actions/learn-github-actions/variables

[thomasrockhu-codecov]

it's slightly less nice for same-repo PRs because in order to populate coverage for your feature branches you'll need CI running on push as well as PR

Is this documented anywhere?

[matt-codecov]

@thomasrockhu-codecov y'know, that's a great question. could you point me to how to update docs and maybe suggest a place for it if one comes to mind?

[thomasrockhu-codecov]

@matt-codecov I think since this is a pretty big paradigm shift, I'd like to pull in @trent-codecov and/or @katia-sentry for their take

for those of you joining us, I don't know the impact this will have on users that don't already run CI on push AND pr events

[matt-codecov]

PR comments should still work for same-repo PRs, i think their coverage will just appear stale in the Codecov website's branch UI because the coverage reports will be filed under refs/pull/#/merge instead of the branch name.

a relevant note from the corresponding codecov-cli PR:

it may be a little while before a fix actually ships. i am away for a couple weeks soon and there are still a few things to work out:

• is the same change needed for other CI providers?
• is there something we can do on the backend to make this change transparent for same-repo PRs?
• if not, what can we do to minimize disruption to that workflow? (doc updates, UI banners, etc)

that said, we're eager to fix this. if it's not solidified before i leave i'll see if any teammates have space to drive it home.

[thomasrockhu-codecov]

linking https://community.codecov.com/t/codecov-reporting-coverage-from-someone-elses-pr-rather-than-main-repos-main/4411/2

[thomasrockhu-codecov]

@matt-codecov any update on this?

[matt-codecov]

just got back from PTO. an alternate approach was noted on the corresponding CLI PR codecov/codecov-cli#237 which i'll look into when i get time again

[matt-codecov]

not continuing with this; the issue is fixed in https://github.com/codecov/codecov-cli and we are working towards deprecating this uploader