Otherwise the cursor position was being reset to 0, even when there was already part of a line, which was strange. Part of #3295.
In case a worker would spawn a new subprocess with process.env, NODE_UNIQUE_ID would have been a part of the env. Making the new subprocess believe it is a worker, this would result in some confusion if the subprocess where to listen to a port, since the server handle request would then be relayed to the worker. This patch removes the NODE_UNIQUE_ID flag from process.env on startup so any subprocess spawned by a worker is a normal process with no cluster stuff.
Fix for joyent/node#3280