The Python documentation states that if the GzipFile can't determine a filename from `fileobj` it'll use an empty string and won't be included in the header. Unfortunately, this doesn't work for SpooledTemporaryFile which has a `name` attribute but doesn't set it initially. The result is a crash.

To reproduce

```
import gzip
import tempfile

with tempfile.SpooledTemporaryFile() as fd:
    with gzip.GzipFile(mode='wb', fileobj=fd) as gz:
        gz.write(b'asdf')
```

Result:
```
Traceback (most recent call last):
  File "<stdin>", line 2, in <module>
  File "/Users/diegoargueta/.pyenv/versions/2.7.14/lib/python2.7/gzip.py", line 136, in __init__
    self._write_gzip_header()
  File "/Users/diegoargueta/.pyenv/versions/2.7.14/lib/python2.7/gzip.py", line 170, in _write_gzip_header
    fname = os.path.basename(self.name)
  File "/Users/diegoargueta/.pyenv/versions/gds27/lib/python2.7/posixpath.py", line 114, in basename
    i = p.rfind('/') + 1
AttributeError: 'NoneType' object has no attribute 'rfind'
```

This doesn't happen on Python 3.6, where the null filename is handled properly. I've attached a patch file that fixed the issue for me.

da, would you mind if I add a test and a news entry to your patch and submit it as a Github pull request?

Yeah that's fine. Thanks!

Did this make it into 2.7.15? There aren't any release notes for it on the download page like usual.

It looks like PR 6095 for this issue has not been reviewed or merged yet.

The commits for v2.7.15 are here:
https://github.com/python/cpython/commits/v2.7.15

Is there someone who might be in a position to review the PR? It's pretty short.

The workaround in the current 2.7 is specifying an explicit filename argument:

with tempfile.SpooledTemporaryFile() as fd:
    with gzip.GzipFile(filename='', mode='wb', fileobj=fd) as gz:
        gz.write(b'asdf')

New changeset afe5f633e49e0e873d42088ae56819609c803ba0 by Serhiy Storchaka (Bo Bayles) in branch '2.7':
bpo-33038: Fix gzip.GzipFile for file objects with a non-string name attribute. (GH-6095)
https://github.com/python/cpython/commit/afe5f633e49e0e873d42088ae56819609c803ba0