The fix is trivial, but I don't understand how
DM-13998 passed Travis on github and then failed on Jenkins for the same issue. Travis caught an earlier example of the same python-2-only error in the same file. But when I fixed that it passed. Since the file was a Python file in examples (and thus never executed by Jenkins) and it passed Travis's pep8 tests and scons's own pep8 tests passed on my machine, I thought it was safe to merge.