GossipChannel.sendDown is the (only) place which creates
GossipSenders. It has two call sites, Send and SendDown, only the
former of which performed a gc of existing senders. Therefore, in
configurations with
- a lot of connection churn, and
- SendDown invocations for these connections, and
- few or no Send invocations
we can leak GossipSenders.
The most likely scenario for this to occur is a peer that, while
having no other connections, is making/accepting connections which get
torn down post handshake, e.g. because IPAM detected a clash.
Fixes#1329.
Matthias Radestock
0b764a2a27