Move the peer_down handling to sender_death, since that's when the slave really
gives up on a sender.

Transplant of 55f7c6afabe0
Merged bug25524 into stable
Receive fixed number of bytes from socket synchronously
Merge bug 25502
If there is no password, refuse access rather than blowing up.
Merge bug25535
Don't make deps.mk depend on generated sources since that seems to cause make to fail silently if it doesn't have the prerequisites to build them.
Junk bug 25537