Python 3.6 SyntaxError attempting to import Flask

[kevinburkefreenome]

When I try to start the tests using Python 3.6, and other issues are resolved, I get the following stack trace.

running build_ext
Traceback (most recent call last):
  File "setup.py", line 110, in <module>
    zip_safe=False
  File "/home/travis/virtualenv/python3.6.3/lib/python3.6/site-packages/setuptools/__init__.py", line 129, in setup
    return distutils.core.setup(**attrs)
  File "/opt/python/3.6.3/lib/python3.6/distutils/core.py", line 148, in setup
    dist.run_commands()
  File "/opt/python/3.6.3/lib/python3.6/distutils/dist.py", line 955, in run_commands
    self.run_command(cmd)
  File "/opt/python/3.6.3/lib/python3.6/distutils/dist.py", line 974, in run_command
    cmd_obj.run()
  File "/home/travis/virtualenv/python3.6.3/lib/python3.6/site-packages/setuptools/command/test.py", line 226, in run
    self.run_tests()
  File "/home/travis/virtualenv/python3.6.3/lib/python3.6/site-packages/setuptools/command/test.py", line 248, in run_tests
    exit=False,
  File "/opt/python/3.6.3/lib/python3.6/unittest/main.py", line 94, in __init__
    self.parseArgs(argv)
  File "/opt/python/3.6.3/lib/python3.6/unittest/main.py", line 141, in parseArgs
    self.createTests()
  File "/opt/python/3.6.3/lib/python3.6/unittest/main.py", line 148, in createTests
    self.module)
  File "/opt/python/3.6.3/lib/python3.6/unittest/loader.py", line 219, in loadTestsFromNames
    suites = [self.loadTestsFromName(name, module) for name in names]
  File "/opt/python/3.6.3/lib/python3.6/unittest/loader.py", line 219, in <listcomp>
    suites = [self.loadTestsFromName(name, module) for name in names]
  File "/opt/python/3.6.3/lib/python3.6/unittest/loader.py", line 190, in loadTestsFromName
    return self.loadTestsFromModule(obj)
  File "/home/travis/virtualenv/python3.6.3/lib/python3.6/site-packages/setuptools/command/test.py", line 52, in loadTestsFromModule
    tests.append(self.loadTestsFromName(submodule))
  File "/opt/python/3.6.3/lib/python3.6/unittest/loader.py", line 153, in loadTestsFromName
    module = __import__(module_name)
  File "/home/travis/build/kevinburkefreenome/flask-restless/tests/helpers.py", line 24, in <module>
    from flask import Flask
  File "/home/travis/virtualenv/python3.6.3/lib/python3.6/site-packages/Flask-0.12.4-py3.6.egg/flask/__init__.py", line 21, in <module>
    from .app import Flask, Request, Response
  File "/home/travis/virtualenv/python3.6.3/lib/python3.6/site-packages/Flask-0.12.4-py3.6.egg/flask/app.py", line 1502
            """
SyntaxError: invalid escape sequence \s

I had to lock the Flask version to version 0.12, otherwise we run into the issue present in #686. It's possible that this version of Flask is simply incompatible with version 3.6.