Stream.prototype.pipe: Don't stop piping when the destination stream …

…emits 'end'.

The 'end' event has nothing to do with the "writable stream-ness" of an object,
and the current behavior breaks a number of use cases with readable/writable
streams.

As far as I can tell the offending line was introduced by accident in 2a65d29.

lib/stream.js

@@ -112,7 +112,6 @@ Stream.prototype.pipe = function(dest, options) {
   source.on('end', cleanup);
   source.on('close', cleanup);
 
-  dest.on('end', cleanup);
   dest.on('close', cleanup);
 
   dest.emit('pipe', source);