[pypy-issue] Issue #2471: dump_rpy_heap throws an exception (pypy/pypy)

[Brian Rak]

New issue 2471: dump_rpy_heap throws an exception
https://bitbucket.org/pypy/pypy/issues/2471/dump_rpy_heap-throws-an-exception

Brian Rak:

```
#!python

# /root/pypy3.3-5.5-alpha-20161013-linux_x86_64-portable/bin/pypy
Python 3.3.5 (ea9979b550eeae87924dc4bef06070e8f8d0e22f, Oct 13 2016, 11:32:23)
[PyPy 5.5.0-alpha0 with GCC 6.2.0] on linux
Type "help", "copyright", "credits" or "license" for more information.
And now for something completely different: ``a 10th of forever is 1h45''
>>>> import gc
>>>> gc.dump_rpy_heap('aaaa')
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: 'str' does not support the buffer interface

```

This works if you pass in a file object instead.  I'd guess it's related to gc.get_typeids_z, as trying to dump to a file this results in a similar error