[FIXED JENKINS-8686]

As I mentioned in the comment, I doubt if this makes any behaviour change, but this seems like a sensible defensive measure that wouldn't hurt.

cli/src/main/java/hudson/cli/CLI.java

@@ -300,14 +300,14 @@ public class CLI {
         byte[] buf = new byte[1024];
         try {
             InputStream is = conn.getInputStream();
-            while (is.read(buf) > 0) {
+            while (is.read(buf) >= 0) {
                 // Ignore
             }
             is.close();
         } catch (IOException e) {
             try {
                 InputStream es = ((HttpURLConnection)conn).getErrorStream();
-                while (es.read(buf) > 0) {
+                while (es.read(buf) >= 0) {
                     // Ignore
                 }
                 es.close();

core/src/main/java/hudson/Proc.java

@@ -399,7 +399,7 @@ public abstract class Proc {
                     try {
                         byte[] buf = new byte[8192];
                         int len;
-                        while ((len = in.read(buf)) > 0) {
+                        while ((len = in.read(buf)) >= 0) {
                             out.write(buf, 0, len);
                             out.flush();
                         }

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

@@ -451,7 +451,7 @@ public class Util {
     public static void copyStream(InputStream in,OutputStream out) throws IOException {
         byte[] buf = new byte[8192];
         int len;
-        while((len=in.read(buf))>0)
+        while((len=in.read(buf))>=0)
             out.write(buf,0,len);
     }
 
@@ -562,7 +562,7 @@ public class Util {
             byte[] buffer = new byte[1024];
             DigestInputStream in =new DigestInputStream(source,md5);
             try {
-                while(in.read(buffer)>0)
+                while(in.read(buffer)>=0)
                     ; // simply discard the input
             } finally {
                 in.close();

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

@@ -57,7 +57,7 @@ public class StreamCopyThread extends Thread {
             try {
                 byte[] buf = new byte[8192];
                 int len;
-                while ((len = in.read(buf)) > 0)
+                while ((len = in.read(buf)) >= 0)
                     out.write(buf, 0, len);
             } finally {
                 // it doesn't make sense not to close InputStream that's already EOF-ed,

core/src/main/java/hudson/util/io/ZipArchiver.java

@@ -71,7 +71,7 @@ final class ZipArchiver extends Archiver {
             zip.putNextEntry(fileZipEntry);
             FileInputStream in = new FileInputStream(f);
             int len;
-            while((len=in.read(buf))>0)
+            while((len=in.read(buf))>=0)
                 zip.write(buf,0,len);
             in.close();
             zip.closeEntry();