Auto merge of rust-lang#42916 - Mark-Simulacrum:update-cargo, r=alexcrichton

Update Cargo

Haven't run extensive tests locally (not really sure what to test) but this primarily pulls in minor changes: rust-lang/cargo#4215, rust-lang/cargo#4209, and rust-lang/cargo#4218. The last one fixes the flaky cargo test by ignoring it, which should unblock rust-lang#42745 -- that's beta nominated.

r? @alexcrichton

Author: bors