Python: modify example 8 to make it consistent with recent update to C example 8
Python: modify example 8 to make it consistent with recent update to C example 8

Tested by Alan W. Irwin <airwin@users.sourceforge.net> on Linux
using the test_diff_psc target.  All Python differences are now gone.

FreeScienceCommunity/PLPlot,FreeScienceCommunity/PLPlot,FreeScienceCommunity/PLPlot,FreeScienceCommunity/PLPlot,FreeScienceCommunity/PLPlot,FreeScienceCommunity/PLPlot,FreeScienceCommunity/PLPlot,FreeScienceCommunity/PLPlot,FreeScienceCommunity/PLPlot