showbase.Transitions crashes with threading-model draw/cull (Mac)

[Bradamante]

Using the Transitions module in direct.showbase works with most configurations. It works with: threading-model /Cull or with no threading-model specified at all. It does crash with: threading-model Cull/Draw, using the fadeIn command, producing this Terminal output ("transitions" being the instanciated Transitions class):

transitions.fadeIn(0.8)
  File "dstroot/pythoncode/Developer/Panda3D/lib/direct/showbase/Transitions.py", line 139, in fadeIn
AssertionError: is_indexed() at line 1353 of panda/src/gobj/geomPrimitive.cxx

Re-producing the fadeIn effect with a custom-made piece of code, where a DirectFrame covers the screen and fades in or out, does not give the crash, no matter what the threading-model configuration is.

Version: Panda3D-2012.08.06-555 (1.8.x build-bot)
Tested hardware: early 2009 iMac, Mac OS X.8.1; mid 2007 MacBookPro, Mac OS X.6.7.

EDIT: Did more testing on both machines. Crashes/Beach-balling also happen with "threading-model /Cull", just less often than with "threading-model Draw/Cull".

[rdb (rdb)]

This was fixed in 1.9.2.