during a build maven sets a class folder instead of a jar file as artifact. ignore.

git-svn-id: https://hudson.dev.java.net/svn/hudson/trunk/hudson/main@2012 71c3de6d-444a-0410-be80-ed276b4c234a

core/src/main/java/hudson/maven/reporters/MavenFingerprinter.java

@@ -92,7 +92,7 @@ public class MavenFingerprinter extends MavenReporter {
      */
     private boolean record(MavenBuildProxy build, final boolean produced, Artifact a) throws IOException, InterruptedException {
         File f = a.getFile();
-        if(f==null || !files.add(f))
+        if(f==null || f.isDirectory() || !files.add(f))
             return false;
 
         // new file