The package "which" includes a file which-2.csh in profile.d which sets up an alias for which for those shells. I find this annoying, prefering the version of which built-in to the shells, since it is more precise and is what I'm used to. I can of course easily fix this for myself with an "unalias" in my .cshrc. But I would guess most tcsh users would have the same opinion, so I suggest the file is removed from the package. (The which-2.sh file is of course quite ok. This is about the (t)csh version only.)
It's fixed in 2.12-3. You will find it in next rawhide