* Added support for running Bitcoin Core as an [I2P (Invisible Internet Project)](https://en.wikipedia.org/wiki/I2P) service and connect to such services. See doc/i2p.md for details. (#20685)
it will only be a problem if some bitcoin node exists which uses SAM 3.2 and "listens" on port 8333 only (checks TO_PORT and drops the incoming connection if it is not 8333)
and it advertises itself as foo:8333 and we change that to foo:0
sgtm. we need something like that if I2P addrs are valid with port number 0 only, which is unfortunate. i don't know of a way to remove or update the existing I2P addrman entries manually from 8333 to 0 (other than deleting peers.dat) so outbound and addnode connections work.
and unfortunate that setting the port number to 0 or ignoring the port number would be necessary for SAM < 3.2, i wonder if the remedy is worse than having (short-lived) double connections
looking at https://geti2p.net/en/docs/api/samv3, SAM 3.2 introduces options FROM_PORT and TO_PORT, and in SAM 3.3, "incoming packets and streams will be routed based on I2P protocol and to-port"
[bitcoin] theStack opened pull request #22330: test: use MiniWallet for simple doublespend sub-test in feature_rbf.py (master...202106-test-feature_rbf_use_miniwallet_for_doublespend) https://github.com/bitcoin/bitcoin/pull/22330