Backport #451 to draft 7.

These are valid here too it'd appear, given draft 7 links to precisely
the same spec for relative json pointers
(https://datatracker.ietf.org/doc/html/draft-handrews-json-schema-validation-01#ref-relative-json-pointer)

Author: Julian

tests/draft7/optional/format/relative-json-pointer.json

@@ -32,6 +32,21 @@
                 "description": "negative prefix",
                 "data": "-1/foo/bar",
                 "valid": false
+            },
+            {
+                "description": "## is not a valid json-pointer",
+                "data": "0##",
+                "valid": false
+            },
+            {
+                "description": "zero cannot be followed by other digits, plus json-pointer",
+                "data": "01/a",
+                "valid": false
+            },
+            {
+                "description": "zero cannot be followed by other digits, plus octothorpe",
+                "data": "01#",
+                "valid": false
             }
         ]
     }