The claimed bug is that when msc_pos is -1 in the code as posted, 'return []' should be executed, but None is returned instead.  When I add 'msc_pos = -1 before the if statement, and call the function, after adding the needed sys import, [] is indeed returned.

The final elif return has two bugs, '%i' and 'Ver':
raise ValueError("Unknown MS Compiler version %i " % msc_Ver)  # Posted
raise ValueError("Unknown MS Compiler version %s " % msc_ver)  # Fixed

With this fix and without -1 forced, the ValueError is raised on all current versions, so this code is out of date in any case.