added a version that does formatting.

git-svn-id: https://hudson.dev.java.net/svn/hudson/trunk/hudson/main@4778 71c3de6d-444a-0410-be80-ed276b4c234a

core/src/main/java/hudson/util/StreamTaskListener.java

@@ -56,8 +56,8 @@ public final class StreamTaskListener implements TaskListener, Serializable {
         return new PrintWriter(new OutputStreamWriter(out),true);
     }
 
-    public void error(String format, Object... args) {
-        out.printf(format,args);
+    public PrintWriter error(String format, Object... args) {
+        return error(String.format(format,args));
     }
 
     public PrintWriter fatalError(String msg) {