Fixed

        if (str[0] == 'q' || str[0] == 'Q')
            break;
To

        if (str.empty() || str[0] == 'q' || str[0] == 'Q')
            break;


[SVN r27813]

libs/spirit

@@ -1 +1 @@
-Subproject commit 9c7874a3d329e09e47b44cd63435420111fce0f7
+Subproject commit ae1d48367c43ee73f844034d71c56c165b28d253