Massaging the fix.

- ID_FORMATTER is time zone sensitive, so comparing against # of
  milliseconds since the epoch won't be portable.

- resolveSymlink can return a relative path.

core/src/main/java/hudson/Util.java

@@ -1094,6 +1094,21 @@ public class Util {
         return resolveSymlink(link);
     }
 
+    /**
+     * Resolves a symlink to the {@link File} that points to.
+     *
+     * @return null
+     *      if the specified file is not a symlink.
+     */
+    public static File resolveSymlinkToFile(File link) throws InterruptedException, IOException {
+        String target = resolveSymlink(link);
+        if (target==null)   return null;
+
+        File f = new File(target);
+        if (f.isAbsolute()) return f;   // absolute symlink
+        return new File(link.getParentFile(),target);   // relative symlink
+    }
+
     /**
      * Resolves symlink, if the given file is a symlink. Otherwise return null.
      * <p>

core/src/main/java/hudson/model/Run.java

@@ -342,10 +342,9 @@ public abstract class Run <JobT extends Job<JobT,RunT>,RunT extends Run<JobT,Run
         try {
             if(Util.isSymlink(buildDir)) {
                 // "Util.resolveSymlink(file)" resolves NTFS symlinks. 
-                String resolvedSymlink = Util.resolveSymlink(buildDir);
-                if(resolvedSymlink != null) {
-                	buildDir = new File(resolvedSymlink);
-                }
+                File target = Util.resolveSymlinkToFile(buildDir);
+                if(target != null)
+                    buildDir = target;
             }
             // canonicalization to ensure we are looking at the ID in the directory name
             // as opposed to build numbers which are used in symlinks

core/src/test/java/hudson/model/RunTest.java

@@ -30,6 +30,7 @@ import hudson.util.StreamTaskListener;
 import java.io.ByteArrayOutputStream;
 import java.io.File;
 import java.nio.charset.Charset;
+import java.util.Date;
 import java.util.TimeZone;
 import java.util.concurrent.Callable;
 import java.util.concurrent.ExecutorService;
@@ -92,13 +93,11 @@ public class RunTest {
     public void testParseTimestampFromBuildDir() throws Exception {
         //Assume.assumeTrue(!Functions.isWindows() || (NTFS && JAVA7) || ...);
         
-        String buildDateTime = "2012-12-21_14-02-28";
-        long buildTimestamp = 1356091348000L;
+        String buildDateTime = "2012-12-21_04-02-28";
         int buildNumber = 155;
         
-        ByteArrayOutputStream baos = new ByteArrayOutputStream();
-        StreamTaskListener l = new StreamTaskListener(baos, Charset.defaultCharset());
-        
+        StreamTaskListener l = StreamTaskListener.fromStdout();
+
         File tempDir = Util.createTempDir();    
         File buildDir = new File(tempDir, buildDateTime);
         assertEquals(true, buildDir.mkdir());
@@ -108,7 +107,8 @@ public class RunTest {
         	buildDir.mkdir();
          
             Util.createSymlink(tempDir, buildDir.getAbsolutePath(), buildDirSymLink.getName(), l);
-            assertEquals(buildTimestamp, Run.parseTimestampFromBuildDir(buildDirSymLink));
+            long time = Run.parseTimestampFromBuildDir(buildDirSymLink);
+            assertEquals(buildDateTime, Run.ID_FORMATTER.get().format(new Date(time)));
         } finally {
             Util.deleteRecursive(tempDir);
         }