I can confirm the problem. It appears to be a stack overflow, when I increase the stack size of the main thead (by adding "-Wl,-stack_size,2faf000" to the link command for BUILDPYTHON) the crash in test_json goes away.

Appearently the default maximum stack size isn't large enough for the default value of the recursion limit.

An easy workaround (fix?) would be to add -Wl,-stack_size,VALUE to the link flags on OSX, for some sane value of VALUE. The value is the maximum size of the stack of the main thread and doesn't affect process size unless a process actually uses more stack space. It does affect the available free address space, and hence the maximum stack size shouldn't be increased too far (especially for 32-bit builds)