Enforce state='file' in copy module

This was causing wrong behaviour when `prev_state` was `hard`-link,
since the `file` module tried to apply the same `state` on the new
file, causing unexpected errors.

Particularly, both `overlay` and `devicemapper` storage drivers in
docker use hardlinks to share files between layers. This causes
most ansible playbooks to fail when working with files from layers
below.

lib/ansible/modules/files/file.py

@@ -250,6 +250,7 @@ def main():
         if basename:
             params['path'] = path = os.path.join(path, basename)
             b_path = to_bytes(path, errors='surrogate_or_strict')
+            prev_state = get_state(b_path)
 
     # make sure the target path is a directory when we're doing a recursive operation
     if recurse and state != 'directory':