Fix AttributeError when the brotli module is installed

[elprans]

The recent addition of Brotli support is broken, since it uses an
incorrect spelling of brotli.error, resulting in:

Python 2.7.16 (default, Mar  8 2019, 14:51:39)
[GCC 8.2.0] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> import urllib3.response
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "site-packages/urllib3/__init__.py", line 7, in <module>
    from .connectionpool import (
  File "site-packages/urllib3/connectionpool.py", line 37, in <module>
    from .response import HTTPResponse
  File "site-packages/urllib3/response.py", line 144, in <module>
    class HTTPResponse(io.IOBase):
  File "site-packages/urllib3/response.py", line 344, in HTTPResponse
    DECODER_ERROR_CLASSES += (brotli.Error,)
AttributeError: 'module' object has no attribute 'Error'

[codecov-io]

Codecov Report

Merging #1572 into master will not change coverage.
The diff coverage is 100%.

@@           Coverage Diff           @@
##           master    #1572   +/-   ##
=======================================
  Coverage   99.89%   99.89%           
=======================================
  Files          22       22           
  Lines        1873     1873           
=======================================
  Hits         1871     1871           
  Misses          2        2

Impacted Files	Coverage Δ
src/urllib3/response.py	100% <100%> (ø)	⬆️

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[sethmlarson]

What version of brotlipy are you using? brotli.Error has been available since 0.5.1.

[elprans]

Hm. We are actually using the google's package (which has the same module name):

https://github.com/google/brotli/blob/4b2b2d4f83ffeaac7708e44409fe34896a01a278/python/brotli.py#L55-L56

[sethmlarson]

That makes sense, we'll have to try testing against that package as well...

[elprans]

brotlipy actually defines the lowercase error as an alias to Error for compatibility with the original brotli module:

https://github.com/python-hyper/brotlipy/blob/ffddf2ea5adc584c8c353d246bb1077b7e781b63/src/brotli/brotli.py#L18-L22

[sethmlarson]

Yeah this fix would definitely work, I'm going to merge this and then start preparing some integration tests so that this isn't an issue in the future and also prepare for a 1.25.1 release.

Thanks for this!

[mnagel]

we require this fix in our product, unfortunately there is no released version of urllib3 containing this fix. what's the schedule for a release including this?

[sethmlarson]

This was released in 1.25.1: https://github.com/urllib3/urllib3/blob/master/CHANGES.rst#1251-2019-04-24