Goroutine leak when closing reverse tunnels
Goroutine leak when closing reverse tunnels

Fixes #468

Sasha, let me know if you want to discuss. It's a small change but if
dont incorrectly can be hard to debug later.

suedadam/teleport,gravitational/teleport,aashley/teleport,tidalf/teleport,sokoow/teleport,aashley/teleport,aashley/teleport,aashley/teleport,suedadam/teleport,bshelton229/teleport,bshelton229/teleport,yacloud-io/teleport,sokoow/teleport,ajvb/teleport,tidalf/teleport,yacloud-io/teleport,sokoow/teleport,bshelton229/teleport,gravitational/teleport,gravitational/teleport,yacloud-io/teleport,tidalf/teleport,bshelton229/teleport,aashley/teleport,bshelton229/teleport,sokoow/teleport,yacloud-io/teleport,tidalf/teleport,yacloud-io/teleport,suedadam/teleport,gravitational/teleport,ajvb/teleport,yacloud-io/teleport,suedadam/teleport,gravitational/teleport,suedadam/teleport,gravitational/teleport,tidalf/teleport,yacloud-io/teleport,sokoow/teleport,ajvb/teleport,ajvb/teleport,sokoow/teleport,ajvb/teleport