JENKINS-8686 IO stream copies are not done properly.

First pass at making sure we don't stop copying when the reader reads 0 characters.

I will now also review the callers for our internal code, and check if we can use IOUtils methods instead.

remoting/src/test/java/hudson/remoting/CopyThread.java

@@ -46,11 +46,14 @@ class Copier extends Thread {
         try {
             byte[] buf = new byte[8192];
             int len;
-            while((len=in.read(buf))>0)
-                out.write(buf,0,len);
-            in.close();
+            try {
+                while((len=in.read(buf))>=0)
+                    out.write(buf,0,len);
+            } finally {
+              in.close();
+            }
         } catch (IOException e) {
-            // TODO: what to do?
+            throw new RuntimeException(e);
         }
     }
 }

remoting/src/test/java/hudson/remoting/TestCallable.java

@@ -45,9 +45,12 @@ public class TestCallable implements Callable {
 
         byte[] buf = new byte[8192];
         int len;
-        while((len=in.read(buf))>0)
-            baos.write(buf,0,len);
-        in.close();
+        try {
+            while((len=in.read(buf))>=0)
+                baos.write(buf,0,len);
+        } finally {
+          in.close();
+        }
 
         r[1] = baos.toByteArray();