We tracked it down to revision 3739 on bzr.dev which happens to be:
3739 Canonical.com Patch Queue Manager 2008-09-26 [merge] (robertc) Create a pyrex optimised iter_changes for dirstate trees. (Robert Collins)
So it seems something in the new iter_changes code causes pyrex 0.9.4.1 to generate code that will cause a segfault.
We tracked it down to revision 3739 on bzr.dev which happens to be:
3739 Canonical.com Patch Queue Manager 2008-09-26 [merge]
(robertc) Create a pyrex optimised iter_changes for dirstate trees.
(Robert Collins)
So it seems something in the new iter_changes code causes pyrex 0.9.4.1 to generate code that will cause a segfault.