cargotest: purge deps

[ishitatsuyuki]

Blocking rust-lang/rust#42588.

[rust-highfive]

Thanks for the pull request, and welcome! The Rust team is excited to review your changes, and you should hear from @matklad (or someone else) soon.

If any changes to this PR are deemed necessary, please add them as extra commits. This ensures that the reviewer can see what has changed since they last reviewed the code. Due to the way GitHub handles out-of-date commits, this should also make it reasonably obvious what issues have or haven't been addressed. Large or tricky changes may require several passes of review and changes.

Please see the contribution instructions for more information.

[matklad]

Huh, it indeed seems useful to know about unused crates!

Thanks, @ishitatsuyuki !

@bors r+

[bors]

📌 Commit 72de74c has been approved by matklad

[bors]

⌛ Testing commit 72de74c with merge d516090...

[bors]

💔 Test failed - status-travis

[ishitatsuyuki]

OSX livelock, please retry.

[matklad]

@bors r+

[bors]

💡 This pull request was already approved, no need to approve it again.

• This pull request previously failed. You should add more commits to fix the bug, or use retry to trigger a build again.

[bors]

📌 Commit 72de74c has been approved by matklad

[bors]

⌛ Testing commit 72de74c with merge 5450163...

[bors]

☀️ Test successful - status-appveyor, status-travis
Approved by: matklad
Pushing 5450163 to master...