Tweaked changeprefix.py to not rename dir component in paths

This wasn't implemented correctly anyways, as it would need to recursively
rename directories that may not exist. Things would also get a bit
complicated if only some files in a directory were renamed.

Doable, but not needed for our use case.

For now just ignore any directory components. Though this may be worth
changing if the source directory structure becomes more complicated in
the future (maybe with a -r/--recursive flag?).

scripts/changeprefix.py

@@ -107,7 +107,10 @@ def main(from_prefix, to_prefix, paths=[], *,
         elif no_renames:
             to_path = from_path
         else:
-            to_path, _ = changeprefix(from_prefix, to_prefix, from_path)
+            to_path = os.path.join(
+                os.path.dirname(from_path),
+                changeprefix(from_prefix, to_prefix,
+                    os.path.basename(from_path))[0])
 
         # rename contents
         changefile(from_prefix, to_prefix, from_path, to_path,