Make Path.append() more forgiving.

git-svn-id: https://svn.apache.org/repos/asf/ant/core/trunk@267899 13f79535-47bb-0310-9956-ffa450edef68

src/main/org/apache/tools/ant/types/Path.java

@@ -181,6 +181,7 @@ public class Path {
      * Append the contents of the other Path instance to this.
      */
     public void append(Path other) {
+        if (other == null) return;
         String[] l = other.list();
         for (int i=0; i<l.length; i++) {
             if (elements.indexOf(l[i]) == -1) {