net: remove misleading comment
The allowHalfOpen comment was added in commit 8a3befa0 ("net: Refactor to use streams2") from 2012 but it wasn't true even then as far as I can tell: Node.js simply always does a shutdown(2) first.
It is true that streams2 withholds the 'end' event when allowHalfOpen
is true but the comment is about a callback that hangs off the 'finish'
event that is emitted after calling socket.end()
.