Description:
In line 156 of /usr/bin/autojump, the map that is traversed is modified while traversing it.
This was fine in Python 2.X since it implicitly copied the keylist before traversal to allow for "concurrent" modifications.
Python 3 no longer does this...

Moving the entry deletion out of this loop into a separate loop traversing the removed list fixes the problem.
(Alternatively you can explicitly copy the key list before traversal, but I guess that would be more compute intensive...)

I am no Python expert and thus did not check the remainder of the script if everything works with Python 3.
Might be worth checking though.

Additional info:
* package version(s)
* config and/or log files etc.

Steps to reproduce:
> j --purge
(Reproduction requires a database with at least one entry to purge; i.e., a directory in the index that does no longer exist)