cherrypicker can't create cherry-pick if PR contains more that 300 files

[dhiller]

What happened:

We recently stumbled over our prow cherrypicker plugin silently failing to create a cherry-pick from one of our pull requests inside the KubeVirt org.

Partial error log (for brevity):

...
"component": "cherrypicker",
  "error": "failed to get patch: status code 406 not one of [200], body: {\"message\":\"Sorry, the diff exceeded the maximum number of files (300). Consider using 'List pull requests files' API or locallycloning the repository instead.\",\"errors\":[{\"resource\":\"PullRequest\",\"field\":\"diff\",\"code\":\"too_large\"}],\"documentation_url\":\"https://docs.github.com/rest/pulls/pulls#list-pull-requests-files\"}",
...

The docs say the maximum for un-paginated access is 3000, where obviously it's "only" 300.

I didn't look at the code, but I suspect that authors did actively neglect the edge case of > 3000 files, which should rarely happen, but did happen in our case.

What you expected to happen:

We expected a cherry-pick to be created on the PR after issuing the /cherry-pick command.

How to reproduce it (as minimally and precisely as possible):
n/a

Please provide links to example occurrences, if any:
kubevirt/application-aware-quota#33 (comment)

Anything else we need to know?:
Apart from this issue I've opened a discussion on GitHub in order to clarify whether it's an API or docs bug.

[dhiller]

/sig ?

[k8s-ci-robot]

@dhiller: The label(s) sig/? cannot be applied, because the repository doesn't have them.

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/sig ?

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[dhiller]

/sig testing

[dhiller]

/area prow