SyntaxError invalid escape sequence "\s"

[stanislavlevin]

I run tests on another python module(custodia), which depends on this one, in such a way:

tox.py3 --sitepackages -v -e py36-noextras -- -v

From custodia's conftest.py:

# deprecated APIs raise an exception
warnings.simplefilter('error', category=DeprecationWarning)

An error message:

    import requests_gssapi
    /usr/lib/python3/site-packages/requests_gssapi/__init__.py:17: in <module>
    from .gssapi_ import HTTPSPNEGOAuth, REQUIRED, OPTIONAL, DISABLED  # noqa
E     File "/usr/lib/python3/site-packages/requests_gssapi/gssapi_.py", line 70
E       regex = re.compile('(?:.*,)*\s*Negotiate\s*([^,]*),?', re.I)
E                         ^
E   SyntaxError: invalid escape sequence \s