Lowering the minimum relay fee is only useful when many nodes in the
p2p network also lower the fee, so to make it easier to understand
progress on that front, this includes the value of the minfeefilter in
getpeerinfo, so you at least have visibility to what fees your neighbours
are currently accepting.
rpc_net.py would intermittently fail on Travis, probably
due to assuming that two consecutive RPC calls were atomic.
Fix this by only testing that amounts are bounded above and
below rather than equal.
