normalization needs to avoid producing empty string.

git-svn-id: https://hudson.dev.java.net/svn/hudson/trunk/hudson/main@28142 71c3de6d-444a-0410-be80-ed276b4c234a

core/src/test/java/hudson/FilePathTest.java

@@ -95,6 +95,9 @@ public class FilePathTest extends ChannelTestCase {
 
         compare("c:\\abc\\..","c:\\");      // we want c:\\, not c:
         compare("c:\\abc\\def\\..","c:\\abc");
+
+        compare("abc/..",".");
+        compare(".",".");
     }
 
     private void compare(String original, String answer) {