[pypy-issue] Issue #2775: crash when building numpy (pypy/pypy)

[mattip]

New issue 2775: crash when building numpy
https://bitbucket.org/pypy/pypy/issues/2775/crash-when-building-numpy

mattip:

Since build ``93883-89245c285fa0`` building numpy produces the following assert error:
```
    RPython traceback:
      File "rpython_jit_metainterp_4.c", line 40838, in MIFrame_run_one_step
      File "rpython_jit_metainterp_6.c", line 55508, in handler_getfield_gc_r_greenfield_1
      File "rpython_jit_metainterp_7.c", line 52040, in MIFrame__opimpl_getfield_gc_greenfield_any
      File "rpython_jit_metainterp_8.c", line 42545, in MIFrame__nonstandard_virtualizable
      File "rpython_jit_metainterp_9.c", line 48872, in MIFrame_emit_force_virtualizable
    Fatal RPython error: AssertionError

```
version ``93876-2ec2d28bba33`` does not fail. To replicate, on a fresh build or a ``tar.gz`` download:

```
pypy -mensurepip
pypy -mpip install cython numpy

It seems the commit in 57349ce40416 somehow reliably triggers the JIT assert
```