1. We assumed an empty upfront_shutdown_script TLV would become NULL:
RPC call failed: method: fundchannel, payload: {'id': '022d223620a359a47ff7f7ac447c85c46c923da53389221a0054c11c1e3ca31d59', 'amount': 1000000, 'announce': True}, error: {'code': -1, 'message': 'They sent error channel e7c2d5d14462fe269631418fbfc3db327843382e6a2a5a9c2991d2d6ba31d9f5: Unacceptable upfront_shutdown_script ', 'data': {'id': '022d223620a359a47ff7f7ac447c85c46c923da53389221a0054c11c1e3ca31d59', 'method': 'fundchannel_start'}}"
2. We were assuming an empty enctlv would become NULL, too.
We should not have done this (there's a semantic difference between
"empty" and not-present for TLVs), so prepare for the change.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>