As part of the fix for #21074, we introduced a test that started flaking. This test requires a ReadableStream to support full cancellation of all outstanding ops before the cancellation promise resolves. Unfortunately, FileResource streams do not have a any sort of read cancellation, and the op_read may last longer than the test itself.

This can likely be repro'd by opening a pipe on linux/windows and cancelling a stream when a read is outstanding.