Auto merge of #3325 - alexcrichton:fix-flaky, r=alexcrichton
Auto merge of #3325 - alexcrichton:fix-flaky, r=alexcrichton

Make a freshness test less flaky

We can't rely on frobbing mtimes, need to actually just wait a whole
second.

nipunn1313/cargo,sbeckeriv/cargo,rust-lang/cargo,eminence/cargo,rust-lang/cargo,vojtechkral/cargo,vojtechkral/cargo,nipunn1313/cargo,nipunn1313/cargo,eminence/cargo,rustyhorde/cargo,durka/cargo,durka/cargo,achanda/cargo,tsurai/cargo,achanda/cargo,tsurai/cargo,achanda/cargo,vojtechkral/cargo,rustyhorde/cargo,nipunn1313/cargo,sbeckeriv/cargo,durka/cargo,tsurai/cargo,rust-lang/cargo,tsurai/cargo,tshepang/cargo,durka/cargo,rustyhorde/cargo,vojtechkral/cargo,rust-lang/cargo,tshepang/cargo,tshepang/cargo,sbeckeriv/cargo,tsurai/cargo,rustyhorde/cargo,tshepang/cargo,sbeckeriv/cargo,eminence/cargo,achanda/cargo,eminence/cargo