Description of problem:

In the Orannon scenario, maybe the last?

Turn 30 (there is no limit to the number of turn, maybe
this is linked).

Before crashing, on the console there is

scenario: 'ano_27'
has snapshot: yes
setting replay to end...
error display: could not open image ''
wesnoth: unit_map.cpp:55: void unit_map::add(std::pair<gamemap::location,
unit>*): Assertion `res.second' failed.
Aborted



Version-Release number of selected component (if applicable):

wesnoth-1.2.7-1.fc8

How reproducible:

Always. But maybe this is linked with my place in the game.

Steps to Reproduce:
1. go to the Orannon scenario in the 'A new order' scenario
2.
3.
  
Actual results:


Expected results:


Additional info:

There are errors before but they are always there, and
certainly linked with other scenarios.