`build-and-deploy` failing on PR submission

[domesticmouse]

From the build logs:

Push the commit or tag
  /usr/bin/git push origin gh-pages
  remote: Permission to flutter/samples.git denied to github-actions[bot].
  fatal: unable to access 'https://github.com/flutter/samples.git/': The requested URL returned error: 403
  Error: Action failed with "The process '/usr/bin/git' failed with exit code 128"

[johnpryan]

I'm not sure why this started happening. @redbrogdon Have we changed how CI / permissions works recently?

[redbrogdon]

I don't believe so. The last commit to that workflow was in August, so that would (I assume) rule out a code change within the repo.

@Hixie or @godofredoc, have there been any changes to the access our GitHub Action workflows have to push to branches within the repo for which they're running?

For context, the deploy script for our hosted demos and samples gallery is failing right at the part where it pushes a commit to the gh-pages branch of this repo:

https://github.com/flutter/samples/runs/3820573303#step:6:1113

[godofredoc]

I don't believe so. The last commit to that workflow was in August, so that would (I assume) rule out a code change within the repo.

@Hixie or @godofredoc, have there been any changes to the access our GitHub Action workflows have to push to branches within the repo for which they're running?

For context, the deploy script for our hosted demos and samples gallery is failing right at the part where it pushes a commit to the gh-pages branch of this repo:

https://github.com/flutter/samples/runs/3820573303#step:6:1113

If the failing step requires write access the permission has to be explicitly defined in the workflow yaml. E.g https://github.com/flutter/flutter/blob/master/.github/workflows/lock.yaml#L11