The blendfile_liblink and blendfile_io python tests in debug fired an
assert that WMWinMan object was in Main database, but not in the ID
name map. This was caused by wm_window_match_do going into case 3
there: the new WM list is completely empty, the old list is not empty,
and it was directly using the old/current list (via
wm_window_match_keep_current_wm function), without actually
registering/validating the objects in it through the name map.
Reviewed By: Bastien Montagne
Differential Revision: https://developer.blender.org/D15787
a1c8a17b4d