Go: cmd/go/internal/renameio: TestConcurrentReadsAndWrites flaky on ios-arm64-corellium builder

[bcmills]

The ios-arm64-corellium builder seems to be affected by the same darwin kernel bug reported in #33041.

Perhaps we should expand the skip for that bug to also apply to ios-arm64-corellium, although it's not obvious to me how we could apply the skip to only the affected kernel.

CC @cherrymui @dmitshur

2020-10-17T00:26:52-a2eb53c/ios-arm64-corellium
2020-10-16T18:54:38-570b49d/ios-arm64-corellium
2020-10-12T17:23:06-1aa43a5/ios-arm64-corellium
2020-10-06T19:39:32-1fb149f/ios-arm64-corellium

[dmitshur]

Also CC @eliasnaur. Any idea if the darwin kernel issue can be resolved on the side of the builder?

[gopherbot]

Change https://golang.org/cl/263777 mentions this issue: cmd/go/internal/renameio: include ios in the darwin test-flake mitigation

[eliasnaur]

The Corellium devices are both iOS 13.1.2. It just so happens that Corellium will move to the Amazon cloud on October 26, after which I have to re-create the devices; I'll see whether iOS 14 is available by then (I can't check without having free CPU cores available)

[bcmills]

Unmarking as release-blocker because the mitigation is in: the test is likely still flaky but the rate should be low enough not to interfere with building releases.

[eliasnaur]

The new Corellium infrastructure has iOS 14.1 available, but it seems unstable:

https://build.golang.org/log/64991503073e69146f7e4b8f47199fd36694d119
https://build.golang.org/log/615269dcecc2a85b76c460bd80760f73e4c1d76b
https://build.golang.org/log/85f76a0bec542a7325494c8bce1a9533feeb7617
https://build.golang.org/log/482cdb1f3e56a18329d3e676d5791b00f62bb5bd

I'm keeping the iOS 13 builders for now.