[Pixman] Bug "In pixman_region_append_non_o: The expression y1 < y2 was false"

[Brent S. Elmer Ph.D.]

I have a Python application that uses gtk through PyGObject.
Occasionally the application will crash.  When I ran the application in
pdb and it crashed, I see these:

*** BUG ***
In pixman_op: The expression r1 != r1_end was false
Set a breakpoint on '_pixman_log_error' to debug

*** BUG ***
In pixman_op: The expression r1 != r1_end was false
Set a breakpoint on '_pixman_log_error' to debug

*** BUG ***
In pixman_region_append_non_o: The expression y1 < y2 was false
Set a breakpoint on '_pixman_log_error' to debug

When I try to set the break I get:

(Pdb) b _pixman_log_error
*** The specified object '_pixman_log_error' is not a function
or was not found along sys.path.

The crashing is not repeatable every time.  I can do the exact same
steps and a lot of the time it won't crash.  The application was
converted from using pygtk.  The pygtk version does not have this
crashing problem.

Any ideas on how to figure out what is causing the crash?