This is not a bug, this is the way python works.  When running in interactive mode (only) the current directory is first on the path.

Now, should this behavior be changed?  I think we've discussed this before and decided not to change it (for backward compatibility reasons), but I think there was dissent and that increasing emphasis on security since that discussion might argue for a different outcome.  It's a python-dev mailing list level issue, in any case.