[pypy-issue] Issue #2395: Pillow no longer works with PyPy2 5.4.0 (SystemError: _PyString_Resize called on already created string) (pypy/pypy)

[Marius Gedminas]

New issue 2395: Pillow no longer works with PyPy2 5.4.0 (SystemError: _PyString_Resize called on already created string)
https://bitbucket.org/pypy/pypy/issues/2395/pillow-no-longer-works-with-pypy2-540

Marius Gedminas:

I've upgraded pypy from version 5.3.1+dfsg-1~ppa1~ubuntu14.04 to version 5.4.0+dfsg-2~ppa1~ubuntu14.04 and if would appear that Pillow can no longer save PNG images.

The traceback looks like this:
```
Traceback (most recent call last):
  File "/var/lib/jenkins/jobs/imgdiff/workspace/.tox/pypy/site-packages/mock/mock.py", line 1305, in patched
    return func(*args, **keywargs)
  File "tests.py", line 61, in test_all_ok
    self.main('example1.png', 'example2.png', '--viewer=true')
  File "tests.py", line 34, in main
    imgdiff.main(['imgdiff'] + list(args))
  File "/var/lib/jenkins/jobs/imgdiff/workspace/imgdiff.py", line 166, in main
    spawn_viewer(opts.viewer, img, name, grace=opts.grace)
  File "/var/lib/jenkins/jobs/imgdiff/workspace/imgdiff.py", line 252, in spawn_viewer
    img.save(imgfile)
  File "/var/lib/jenkins/jobs/imgdiff/workspace/.tox/pypy/site-packages/PIL/Image.py", line 1685, in save
    save_handler(self, fp, filename)
  File "/var/lib/jenkins/jobs/imgdiff/workspace/.tox/pypy/site-packages/PIL/PngImagePlugin.py", line 792, in _save
    [("zip", (0, 0)+im.size, 0, rawmode)])
  File "/var/lib/jenkins/jobs/imgdiff/workspace/.tox/pypy/site-packages/PIL/ImageFile.py", line 479, in _save
    l, s, d = e.encode(bufsize)
SystemError: _PyString_Resize called on already created string
```

Steps to reproduce:

1. git clone https://github.com/mgedmin/imgdiff
2. cd imgdiff
3. tox -e pypy