When we got our peer's sigs, if we were the remote, we would re-notify
the plugin, which in turn would re-send the tx-sigs to use.
In the case of CLN, we'd then
- break, because we'd re-forward the sigs to the `openchannel` plugin,
which was then in the wrong state (MULTIFUNDCHANNEL_SIGNED)
spenderp: plugins/spender/openchannel.c:598: json_peer_sigs: Assertion `dest->state == MULTIFUNDCHANNEL_SECURED' failed.
spenderp: FATAL SIGNAL 6 (version 5880d59-modded)
In the case of eclair, they'd just see our 2nd TX_SIGS message and
@t-bast would complain:
> This test works, with one minor issue: on reconnection, cln sends its tx_signatures twice (duplicate?).
This commit does two things:
- has the openchannel / spender plugin log a broken instead of
crashing when the state is not what we're expecting
- stops us from calling the `funder` plugin if this is a
replay/second receipt of commit-sigs.