fix(responsemanager): send update while completing

[hannahhoward]

If request has finished selector traversal but is still sending blocks, I think it should be possible to send updates. As a side effect, this fixes our test race.

Logically, this makes sense, cause our external indicator that we're done (completed response listener) has not been called.

[rvagg]

oh, interesting catch! thanks for figuring this one out, I wouldn't have got that I think