rustpkg::tests::test_package_request_version fails on Linux

[catamorphism]

(From a commit I'm about to re-approve.) I don't know why, and can't get the VPN to work so I can experiment on the Linux bot.

[catamorphism]

In the logs for #7040, this also failed on Mac

[alexcrichton]

I'm not sure if this would be related, but it looks like it's contacting github which I've seen fail on the bots occasionally. Maybe sporadic failures could be github network trouble?

[catamorphism]

@alexcrichton Could be. I'm not sure what to do about it, though; github can be flaky, but I want to have tests for remote packages.

[alexcrichton]

Is this still an issue? I thought I saw a commit go by awhile back which used a local repo instead of a remote git repo. If we still use a remote, though, carry on :)

[catamorphism]

Somehow, this test lost its #[test] attribute. Re-testing.

[catamorphism]

This can close when #8570 lands