(PR#20759) Crash on box select + mass goto

<URL: 
http://bugs.freeciv.org/Ticket/Display.html?id=20759
>

Local game vs AIs

Using the box select I chose a bunch of units which included
armor and
engineers.
Then after shifting the map (right click - which seems the
only way to
give a box select command); I used g to send all the units
to one
enemy city and the game crashed.

I tried this a couple times and it did crash each time.



Also noticed that all backups seem to have the normal
players as AI
(this may be emergency saves if that is what happens), which
usually
means you need to start a new game since the AI will mess up
your
builds.