Auto merge of #5564 - mati865:metadata_fix, r=alexcrichton

Always replace metadata when replacing package

Fixes https://github.com/rust-lang/cargo/issues/4582

I'm having problem writing test for it.
The test should install binary, make commit and reinstall binary, this part is done.
To know if it was done properly we need to compare git revision of HEAD and installed binary and that's where the problems begin...