By adding to the test framework a wait until the v2 handshake
is completed, so that p2p_sendtxrcncl.py (which doesn't need
to be changed itself) doesnt't send out any other messages before that.
- A node initiates a v2 connection by sending 64 bytes ellswift
- In BIP 324 "The responder waits until one byte is received which does not match the
V1_PREFIX (16 bytes consisting of the network magic followed by "version\x00\x00\x00\x00\x00".)"
- It's possible that the 64 bytes ellswift sent by an initiator starts with a prefix of V1_PREFIX
- Example form of 64 bytes ellswift could be:
4 bytes network magic + 60 bytes which aren't prefixed with remaining V1_PREFIX
- We test this behaviour:
- when responder receives 4 byte network magic -> no response received by initiator
- when first mismatch happens -> response received by initiator
