Debian's which hunt

Yes, this is the first time I have encountered "command -v". How are we supposed to have heard of it? Who decided it should be the real Posixy thing, and "which" not?

It should be a pretty small effort to replace uses of "which" in packages that use it. After that, replacing "which" itself with a one-liner that says "use command -v" then "exit 1" is another small effort. Moving it out of the package it is in seems like pointless extra work.