stealConnection
"Steals" the HTTP connection associated with @msg from its #SoupServer. This happens immediately, regardless of the current state of the connection; if the response to @msg has not yet finished being sent, then it will be discarded; you can steal the connection from a signal@ServerMessage::wrote-informational or signal@ServerMessage::wrote-body signal handler if you need to wait for part or all of the response to be sent.
Note that when calling this function from C, @msg will most likely be freed as a side effect.
Return
the #GIOStream formerly associated with @msg (or null if @msg was no longer associated with a connection). No guarantees are made about what kind of #GIOStream is returned.