Fix some PATH manipulation issues that occurred for the MinGW/MSYS interactive test case.
Fix some PATH manipulation issues that occurred for the MinGW/MSYS
interactive test case.

svn path=/trunk/; revision=12991

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