Fix(?) construction of path for File() copies.
Fix(?) construction of path for File() copies.

Andre, can you please review? I changed the implementation of that method, but
to be honest, I don't necessarily get what it is supposed to do.

telamonian/saga-python,luis-rr/saga-python,luis-rr/saga-python,telamonian/saga-python,mehdisadeghi/saga-python,mehdisadeghi/saga-python,luis-rr/saga-python