MAINT: fix runtests.py issue when run with ``python -OO``
MAINT: fix runtests.py issue when run with ``python -OO``

PyWavelets/pywt,ThomasA/pywt,aaren/pywt,PyWavelets/pywt,kwohlfahrt/pywt,aaren/pywt,eriol/pywt,grlee77/pywt,michelp/pywt,michelp/pywt,kwohlfahrt/pywt,michelp/pywt,ThomasA/pywt,eriol/pywt,rgommers/pywt,eriol/pywt,rgommers/pywt,kwohlfahrt/pywt,rgommers/pywt,ThomasA/pywt,aaren/pywt,grlee77/pywt,rgommers/pywt