Fix random Windows CI error for changing_bin_features_caches_targets

[ehuss]

Fixes #5481.

[rust-highfive]

r? @matklad

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[ehuss]

I've been doing some stress tests on AppVeyor, and I have been unable to get it to fail with this change. An alternative solution would be to unlink the file and attempt to replace it in a loop until it succeeds.

[alexcrichton]

Thanks! I wonder though if in this situation instead of cargo run this could execute cargo build? Then it could copy the binary somewhere else to run it and make an assert about the output, and hopefully that'll avoid the can't-delete-after-exec problem?

[ehuss]

copy the binary somewhere else to run

Sure! I'll try that soon!

[matklad]

I think one can use —out-directory flag to avoid coping by hand

[ehuss]

Updated with new approach. I stressed this on AppVeyor for a while and it seems OK.

[matklad]

@bors r+

Awesome!

[bors]

📌 Commit 3521144 has been approved by matklad

[bors]

⌛ Testing commit 3521144 with merge 9e53ac6...

[bors]

☀️ Test successful - status-appveyor, status-travis
Approved by: matklad
Pushing 9e53ac6 to master...