vlib: fix https://trac.osgeo.org/grass/changeset/55643 (is_isle)

git-svn-id: https://svn.osgeo.org/grass/grass/trunk@55709 15284696-431f-4ddb-bdfa-cd5b030d7da7

lib/vector/Vlib/copy.c

@@ -355,7 +355,7 @@ int is_isle(const struct Map_info *Map, int area)
         if (1 != Vect_get_line_areas(Map, abs(line), &left, &right))
             continue;
         
-        isle = line > 0 ? right : left;
+        isle = line > 0 ? left : right;
         
         if (isle < 0 && Vect_get_isle_area(Map, abs(isle)) > 0) {
             is_isle = TRUE;