- development of a new protocol version. This exchange of sub-version
- info does not interfere with the {MIN,MAX}_PROTOCOL_VERSION checking
- in older versions (since we'd quickly exceed the MAX_PROTOCOL_VERSION
- if we incremented the main PROTOCOL_VERSION value for every minor
- change during development).
+ development of a new protocol version. This causes any out-of-sync
+ versions to speak an older protocol rather than fail in a cryptic manner.
+ This addition makes it safe to deploy a pre-release version that may
+ interact with the public. This new exchange of sub-version info does not
+ interfere with the {MIN,MAX}_PROTOCOL_VERSION checking algorithm (which
+ does not have enough range to allow the main protocol number to be
+ incremented for every minor tweak in that happens during development).