Lists of changed files of pull-requests are empty

[anbraten]

Component

server

Describe the bug

pipeline:
  build:
    image: node:14-alpine
    commands:
      - cd docs/
      - yarn install --frozen-lockfile
      - yarn build
    when:
      event: [push, pull_request]
      path: "docs/**"

Step is executed although no file in docs/** has been changed.

System Info

{"source":"https://github.com/woodpecker-ci/woodpecker","version":"next-7931bc78"}

Additional context

https://ci.woodpecker-ci.org/woodpecker-ci/woodpecker/build/1317

Validations

• Read the Contributing Guidelines.
• Read the docs.
• Check that there isn't already an issue that reports the same bug to avoid creating a duplicate.
• Check that this is a concrete bug. For Q&A join our Discord Chat Server.

[anbraten]

It seems to work in general. One problem I saw is that changed_files for a commit of a PR only includes the changes of that single commit instead of all changes of the PR. This is felt somehow wrong to me and does not allow to use path changes as for example the woodpecker project itself is currently trying to.

[anbraten]

Looking at https://docs.github.com/en/developers/webhooks-and-events/webhooks/webhook-events-and-payloads#webhook-payload-example-32 shows that the list of changed files isn't part of the webhook payload, so we have to get it via a separate api call for github.

Github: https://docs.github.com/en/rest/reference/pulls#list-pull-requests-files
Gitea: go-gitea/gitea#654
Gitlab: https://docs.gitlab.com/ee/api/merge_requests.html#get-single-mr-changes