gsutil Exception TypeError: "'NoneType' object is not callable" after python 2.7.11 -> 2.7.13

I have upgraded Python in Debian from 2.7.11-2 to 2.7.13-2 and now gsutil says this for all commands:
```
$ gsutil --version |& uniq -c
1 gsutil version: 4.27
31 Exception TypeError: "'NoneType' object is not callable" in ignored
```

here's showing some more information on the files, but not sure why there is no more precise location or stack trace that's shown, but at least it shows the file:
```
$ CLOUDSDK_PYTHON_ARGS=-v gsutil --version |& grep -C 3 NoneType | uniq -c
1 # cleanup[2] email.base64mime
1 # cleanup[2] email.mime.multipart
1 # cleanup[2] gslib.copy_helper
6 Exception TypeError: "'NoneType' object is not callable" in ignored
1 # cleanup[2] Crypto.Random.Fortuna
1 # cleanup[2] pyasn1_modules.pem
1 # cleanup[2] boto.gs.lifecycle
1 --
1 # cleanup[2] Crypto.Hash.SHA256
1 # cleanup[2] re
1 # cleanup[2] gslib.command
25 Exception TypeError: "'NoneType' object is not callable" in ignored
1 # cleanup[2] math
1 # cleanup[2] rsa.transform
1 # cleanup[2] simplejson.scanner
```

not sure if this is more appropriately a python or debian bug. it appears to be only a usage warning -- everything works -- but it happens all over the place.