added BORG_MSGPACK_VERSION_CHECK, no test

borgmatic/borg/environment.py

@@ -13,6 +13,7 @@ OPTION_TO_ENVIRONMENT_VARIABLE = {
     'borg_key_file': 'BORG_KEY_FILE',
     'ssh_command': 'BORG_RSH',
     'temporary_directory': 'TMPDIR',
+    'msgpack_version_check': 'BORG_MSGPACK_VERSION_CHECK',
 }
 
 DEFAULT_BOOL_OPTION_TO_UNCONDITIONAL_ENVIRONMENT_VARIABLE = {

borgmatic/config/schema.yaml

@@ -570,6 +570,12 @@ properties:
             Bypass Borg confirmation about check with repair option. Defaults to
             false and an interactive prompt from Borg.
         example: true
+    msgpack_version_check:
+        type: string
+        description: |
+            optionally disable the msgpack version check.
+            Default is “yes”; use at your own risk.
+        example: yes
     extra_borg_options:
         type: object
         additionalProperties: false