queen_attack: replace assertFalse with assertIs
queen_attack: replace assertFalse with assertIs

mweb/python,exercism/python,N-Parsons/exercism-python,behrtam/xpython,behrtam/xpython,pheanex/xpython,smalley/python,exercism/xpython,jmluy/xpython,smalley/python,mweb/python,exercism/python,pheanex/xpython,N-Parsons/exercism-python,jmluy/xpython,exercism/xpython