fix bug introduced in test_filtering to test the testing script
fix bug introduced in test_filtering to test the testing script

mne-tools/mne-cpp,chdinh/mne-cpp,chdinh/mne-cpp,chdinh/mne-cpp,chdinh/mne-cpp,mne-tools/mne-cpp,mne-tools/mne-cpp,mne-tools/mne-cpp,mne-tools/mne-cpp,chdinh/mne-cpp,chdinh/mne-cpp,mne-tools/mne-cpp