A fault due to a version mismatch or a feature set mismatch used to be
treated differently from other faults: the connection would get closed
without trying to reconnect and there was a ->bad_proto() connection op
for notifying about that.

This changed a long time ago, see commits 6384bb8b ("libceph: kill
bad_proto ceph connection op") and 0fa6ebc6 ("libceph: fix protocol
feature mismatch failure path").  Nowadays these aren't any different
from other faults (i.e. we try to reconnect even though the mismatch
won't resolve until the server is replaced).  reset_connection() calls
there are rather confusing because reset_connection() resets a session
together an individual instance of the protocol.  This is cleaned up
in the next patch.
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>