fix dealing with remote repo LockTimeout

previously, this was handled in RPCError handler and always resulted in rc 2.

now re-raise LockTimeout locally, so it gives rc 2 (legacy) or 73 (modern).

src/borg/archiver.py

@@ -5314,7 +5314,7 @@ def main():  # pragma: no cover
             tb = f"{traceback.format_exc()}\n{sysinfo()}"
             exit_code = e.exit_code
         except RemoteRepository.RPCError as e:
-            important = e.exception_class not in ('LockTimeout', ) and e.traceback
+            important = e.traceback
             msgid = e.exception_class
             tb_log_level = logging.ERROR if important else logging.DEBUG
             if important:

src/borg/remote.py

@@ -27,6 +27,7 @@
 from .helpers import format_file_size
 from .helpers import safe_unlink
 from .helpers import prepare_subprocess_env, ignore_sigint
+from .locking import LockTimeout
 from .logger import create_logger, setup_logging
 from .helpers import msgpack
 from .repository import Repository
@@ -779,6 +780,11 @@ def handle_error(unpacked):
                     raise InvalidRPCMethod('(not available)')
                 else:
                     raise InvalidRPCMethod(args[0].decode())
+            elif error == 'LockTimeout':
+                if old_server:
+                    raise LockTimeout('(not available)')
+                else:
+                    raise LockTimeout(args[0].decode())
             else:
                 raise self.RPCError(unpacked)