This is fairly simple. We do all the prep work, fire off the child,
and it continues all the way to producing JSON output (or an error).
The parent then forwards it.
Limitations (fixed in successive patches):
1. Child logging currently gets lost.
2. We wait for the child, so this code is not a speedup.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Any file in this directory which is executable and whose name only
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automatically loaded when lightningd starts (unless suppressed with
commandline options).
0ede29b81f