Does this not result in a drop of the whole path still, thus change behaviour also on linux?
E.g. with _tgtdir=(C:)/target and _file=(C:)/some/path/file before the target path would be (C:)/target(C:)/some/path/file, where it now will be (C:)/target/file.

I could not see where we actually pass absolute filepaths to COPY_FILES, possibly never hit this. But this change seems breaking the current behaviour.