tx_broadcast set to "not-self" does not work

[AlexCato]

Fixed a bug already in #365 , but even with this fix, the TX does not get broadcast. @kristapsk noticed the same, see the #365 .

Just writing this down here so this is not forgotten:

So far, tested on mainnet:
Taker does send the push command to a maker according to logs. That command never is seen on the maker side, at least there is no log entry whatsoever about this private message from the taker.

This is the taker side:

2019-07-08 15:42:15,231 [DEBUG]  Created watcher loop for txid: <TXID>
2019-07-08 15:42:15,240 [DEBUG]  >>privmsg on DarkScience: nick=<MAKERNAME> cmd=push msg=<SUPERLONG_STRING>
2019-07-08 15:44:18,243 [INFO]  Abandoning monitoring of un-broadcast tx for: <TXID>
2019-07-08 15:48:05,142 [INFO]  STALL MONITOR:
2019-07-08 15:48:05,142 [INFO]  Tx was already pushed; ignoring

[AdamISZ]

Sorry I was busying addressing two other issues yesterday so didn't pay attention to this, but see:

https://github.com/JoinMarket-Org/joinmarket-clientserver/blob/master/jmdaemon/jmdaemon/daemon_protocol.py#L449

It's been discussed a few times, I thought you knew (my mistake, I can't assume everyone just knows everything that gets discussed) basically it's one of a number of things I was hoping would get fixed up later.

[AdamISZ]

I added the label "bug" because it really is a bug that this setting exists but is not implemented (even if we fixed a crash from it). The context matters; this feature existed in the old version and was always intended in the new version, but was never done. There is a reason why it's a little more than trivial, otherwise I would have done it at the start. So it's a bug but it's also an enhancement :)