fix 'except' to specify 'ImportError' correctly
fix 'except' to specify 'ImportError' correctly

Peque/xpython,mweb/python,pombredanne/xpython,outkaj/xpython,jmluy/xpython,rootulp/xpython,exercism/xpython,rootulp/xpython,exercism/python,oalbe/xpython,smalley/python,exercism/xpython,smalley/python,pheanex/xpython,ZacharyRSmith/xpython,N-Parsons/exercism-python,jmluy/xpython,de2Zotjes/xpython,pheanex/xpython,de2Zotjes/xpython,wobh/xpython,behrtam/xpython,exercism/python,pombredanne/xpython,wobh/xpython,N-Parsons/exercism-python,Peque/xpython,ZacharyRSmith/xpython,orozcoadrian/xpython,mweb/python,outkaj/xpython,oalbe/xpython,orozcoadrian/xpython,behrtam/xpython