config-mgmt: T5353: after updated save-config, one can include init rev

The legacy config-mgmt/save-config tools had an abiding bug that would
raise an error if comparing/reading the init archive; this is no longer
an issue.

(cherry picked from commit 52e4b44)

python/vyos/config_mgmt.py

@@ -526,9 +526,8 @@ def _get_number_of_revisions(self) -> int:
         return len(l)
 
     def _check_revision_number(self, rev: int) -> bool:
-        # exclude init revision:
         maxrev = self._get_number_of_revisions()
-        if not 0 <= rev < maxrev - 1:
+        if not 0 <= rev < maxrev:
             return False
         return True