Changes in remoting make wrapping IOException less necessary.

Still do it so we capture FilePath.remote (which many JRE methods suppress),
but fix the wrapper Throwable.message to include cause.toString() according to convention.

core/src/main/java/hudson/FilePath.java

@@ -943,7 +943,7 @@ public final class FilePath implements Serializable {
                 throw e;    // pass through so that the caller can catch it as AbortException
             } catch (IOException e) {
                 // wrap it into a new IOException so that we get the caller's stack trace as well.
-                throw new IOException2("remote file operation failed: "+remote+" at "+channel,e);
+                throw new IOException("remote file operation failed: " + remote + " at " + channel + ": " + e, e);
             }
         } else {
             // the file is on the local machine.