slowscan has been broken, no idea since when.

git-svn-id: https://svn.apache.org/repos/asf/ant/core/trunk@727739 13f79535-47bb-0310-9956-ffa450edef68

src/main/org/apache/tools/ant/DirectoryScanner.java

@@ -1096,6 +1096,8 @@ public class DirectoryScanner
                 String[] notIncl = new String[dirsNotIncluded.size()];
                 dirsNotIncluded.copyInto(notIncl);
 
+                ensureNonPatternSetsReady();
+
                 processSlowScan(excl);
                 processSlowScan(notIncl);
                 clearCaches();