Bug#912533: lasagne's autopkg tests fail with python3.7 as the default python3

[Matthias Klose]

Package: src:lasagne
Version: 0.1+git20180322.37ca134-1
Severity: important
Tags: sid buster

lasagne's autopkg tests fail with python3.7 as the default python3, emitting a
warning on stderr:

autopkgtest [23:39:52]: test pytest-py3: [-----------------------
============================= test session starts ==============================
platform linux -- Python 3.7.1, pytest-3.6.4, py-1.6.0, pluggy-0.6.0
rootdir: /tmp/autopkgtest.O5mbFt/build.x4Z/src, inifile:
plugins: pep8-1.0.6, cov-2.5.1
collected 333 items

test_init.py ....................................                        [ 10%]
test_nonlinearities.py ...............                                   [ 15%]
test_objectives.py .............................                         [ 24%]
test_regularization.py .......                                           [ 26%]
test_updates.py ........................                                 [ 33%]
test_utils.py .............................                              [ 42%]
layers/test_base.py ...................                                  [ 47%]
layers/test_dense.py .............................ssssssss               [ 58%]
layers/test_helper.py .................................................. [ 73%]
.                                                                        [ 74%]
layers/test_input.py .........                                           [ 76%]
layers/test_shape.py ..............................                      [ 85%]
layers/test_special.py ...............................................   [100%]

==================== 325 passed, 8 skipped in 29.43 seconds ====================
/usr/lib/python3/dist-packages/pep8.py:110: FutureWarning: Possible nested set
at position 1
  EXTRANEOUS_WHITESPACE_REGEX = re.compile(r'[[({] | []}),;:]')
autopkgtest [23:40:23]: test pytest-py3: -----------------------]
pytest-py3           FAIL stderr: /usr/lib/python3/dist-packages/pep8.py:110:
FutureWarning: Possible nested set at position 1
autopkgtest [23:40:24]: test pytest-py3:  - - - - - - - - - - results - - - - -
- - - - -
autopkgtest [23:40:24]: test pytest-py3:  - - - - - - - - - - stderr - - - - - -
- - - -
/usr/lib/python3/dist-packages/pep8.py:110: FutureWarning: Possible nested set
at position 1
  EXTRANEOUS_WHITESPACE_REGEX = re.compile(r'[[({] | []}),;:]')