merge bitcoin#20524: Move MIN_VERSION_SUPPORTED to p2p.py

continuation of cbff29a6 (dash#6067)

test/functional/test_framework/test_node.py

@@ -27,6 +27,7 @@ from .descriptors import descsum_create
 from .p2p import P2P_SUBVERSION
 from .util import (
     MAX_NODES,
+    assert_equal,
     append_config,
     delete_cookie_file,
     get_auth_cookie,
@@ -637,6 +638,11 @@ class TestNode():
             # in comparison to the upside of making tests less fragile and unexpected intermittent errors less likely.
             p2p_conn.sync_with_ping()
 
+            # Consistency check that the Dash Core has received our user agent string. This checks the
+            # node's newest peer. It could be racy if another Dash Core node has connected since we opened
+            # our connection, but we don't expect that to happen.
+            assert_equal(self.getpeerinfo()[-1]['subver'], p2p_conn.strSubVer)
+
         return p2p_conn
 
     def add_outbound_p2p_connection(self, p2p_conn, *, p2p_idx, connection_type="outbound-full-relay", **kwargs):