Clobbering a folder with a file is broken

[wolfv]

I found a situation where a folder is clobbered by a file. This currently is broken with rattler as we try to remove the folder as if it was a file (that fails).

The situation comes from installing libcxx and clang_bootstrap_osx-arm64 15.* at the same time.

I am not sure what we should do. Maybe we should change the logic and move clobbering files (or folders) to a special directory (e.g. $PREFIX/clobber/<tree>)? Or special case folders that are clobbered in a different way.