diff --git a/core/src/main/java/hudson/util/StreamCopyThread.java b/core/src/main/java/hudson/util/StreamCopyThread.java
index e494afa9b947..8df8c4171ee6 100644
--- a/core/src/main/java/hudson/util/StreamCopyThread.java
+++ b/core/src/main/java/hudson/util/StreamCopyThread.java
@@ -63,8 +63,11 @@ public void run() {
                 // it doesn't make sense not to close InputStream that's already EOF-ed,
                 // so there's no 'closeIn' flag.
                 in.close();
-                if(closeOut)
+                if (closeOut) {
                     out.close();
+                } else {
+                    out.flush();
+                }
             }
         } catch (IOException e) {
             // TODO: what to do?
diff --git a/core/src/main/java/hudson/util/StreamTaskListener.java b/core/src/main/java/hudson/util/StreamTaskListener.java
index b2b2e4fd62e3..d70a905920a6 100644
--- a/core/src/main/java/hudson/util/StreamTaskListener.java
+++ b/core/src/main/java/hudson/util/StreamTaskListener.java
@@ -169,7 +169,7 @@ private void writeObject(ObjectOutputStream out) throws IOException {
     }
 
     private void readObject(ObjectInputStream in) throws IOException, ClassNotFoundException {
-        out = new PrintStream((OutputStream)in.readObject(),true);
+        out = new PrintStream((OutputStream)in.readObject(), false);
         String name = (String)in.readObject();
         charset = name==null ? null : Charset.forName(name);
     }