Only update stream status and not label

For every stream, tor will send something like:

650 STREAM 3709 NEW 0 www.example.org:80 SOURCE_ADDR=127.0.0.1:42592 PURPOSE=USER
650 STREAM 3709 SENTCONNECT 95 www.example.org:80
650 STREAM 3709 REMAP 95 93.184.216.34:80 SOURCE=EXIT
650 STREAM 3709 SUCCEEDED 95 93.184.216.34:80
650 STREAM 3709 CLOSED 95 93.184.216.34:80 REASON=DONE

If we update the target when we receive the REMAP event, then we replace the
hostname by its IP. In this commit we only update the stream status, but keep
the old target.