Tests fail due to a missing extra: pycvodes

[yurivict]

___________________________________________________________ ERROR collecting pyodesys/native/tests/test_odeint.py ___________________________________________________________
ImportError while importing test module '/usr/ports/math/py-pyodesys/work-py27/pyodesys-0.12.3/pyodesys/native/tests/test_odeint.py'.
Hint: make sure your test modules/packages have valid Python names.
Traceback:
pyodesys/native/__init__.py:14: in <module>
    from .cvode import NativeCvodeSys
pyodesys/native/cvode.py:18: in <module>
    class NativeCvodeCode(_NativeCodeBase):
pyodesys/native/cvode.py:22: in NativeCvodeCode
    _realtype = _config.env.get('REAL_TYPE', 'double')
pyodesys/util.py:272: in __getattribute__
    raise self._exc  # ImportError("Failed to import %s" % self._modname)
E   ImportError: No module named pycvodes
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! Interrupted: 3 errors during collection !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

Extra dependencies are optional, and should only cause test warnings.

[bjodah]

I believe this is due to pycvodes being installed but not functional. (tests without extra dependencies are exercised in the CI setup). Once Python >=3.6 can be made a requirement it should be possible to discern ImportError from ModuleNotFoundError and then the exception can be a bit more informative.