--which-module and -w are not applied, but --only and -o work properly

Specifically on Linux Mint 19 here, but this has been an issue for me for a while for me that I figured was just me using it wrong including on Windows and Mac if I'm not mistaken.

Start with the CLI handling for --which-module/-w and compare it with --only/-o, using the reported Linux Mint case if reproducible. Confirm the failure and trace where each option is parsed and applied; done means both aliases consistently restrict the rebuild target on supported platforms.

Written by the indexing model from the issue text.