Avoid NullPointerException in JDK 1.1

git-svn-id: https://svn.apache.org/repos/asf/ant/core/trunk@268370 13f79535-47bb-0310-9956-ffa450edef68

src/main/org/apache/tools/ant/taskdefs/Zip.java

@@ -23,7 +23,7 @@
  *    Alternately, this acknowlegement may appear in the software itself,
  *    if and wherever such third-party acknowlegements normally appear.
  *
- * 4. The names "The Jakarta Project", "Tomcat", and "Apache Software
+ * 4. The names "The Jakarta Project", "Ant", and "Apache Software
  *    Foundation" must not be used to endorse or promote products derived
  *    from this software without prior written permission. For written 
  *    permission, please contact apache@apache.org.
@@ -486,7 +486,12 @@ public class Zip extends MatchingTask {
 
         while (!directories.isEmpty()) {
             String dir = (String) directories.pop();
-            File f = new File(baseDir, dir);
+            File f = null;
+            if (baseDir != null) {
+                f = new File(baseDir, dir);
+            } else {
+                f = new File(dir);
+            }
             zipDir(f, zOut, prefix+dir);
         }
     }