rpc: reset transport version on connect

This is needed for the case in which a peer on the other end of a
reconnect_transport is downgraded. unless we reset the version on
reconnect then we'll get a policy violation if the peer responds
with a lower version than the transport had been upgraded to.

Signed-off-by: Noah Watkins <noahwatkins@gmail.com>

src/v/rpc/transport.cc

@@ -83,6 +83,7 @@ void transport::reset_state() {
     _correlation_idx = 0;
     _last_seq = sequence_t{0};
     _seq = sequence_t{0};
+    _version = transport_version::v1;
 }
 
 ss::future<>

src/v/rpc/transport.h

@@ -112,6 +112,8 @@ class transport final : public net::base_transport {
      * version level used when dispatching requests. this value may change
      * during the lifetime of the transport. for example the version may be
      * upgraded if it is discovered that a server supports a newer version.
+     *
+     * reset to v1 in reset_state() to support reconnect_transport.
      */
     transport_version _version{transport_version::v1};