Type checker doesn't respect capabilities allow_net for remote schemas

[johanfylling]

Given the following capabilities.json file, that disallows all outbound network connections:

{
   ...
   "allow_net": []
}

and the following Rego file, that has an inlined schema with a reference to some schema hosted at some web server (this server doesn't need to exist for this example):

package test

# METADATA
# schemas:
# - input: {"$ref": "http://localhost:8000/schema.json"}
q {
    input == 42
}

When running opa eval --capabilities capabilities.json -s schemas -d policy.rego data (the schemasfolder doesn't need to contain any schemas, it's just required for the type-checker to utilize the schemas annotation), we expect the following error, on account of no remote hosts being allowed by capabilities.json:

{
  "errors": [
    {
      "message": "unable to compile the schema: remote reference loading disabled: http://localhost:8000/schema.json",
      "code": "rego_type_error",
      "location": {
        "file": "policy.rego",
        "row": 6,
        "col": 1
      }
    }
  ]
}

but we get the following error, as OPA attempts to fetch the schema (no server listener present on localhost:8000:

{
  "errors": [
    {
      "message": "unable to compile the schema: Get \"http://localhost:8000/schema.json\": dial tcp [::1]:8000: connect: connection refused",
      "code": "rego_type_error",
      "location": {
        "file": "policy.rego",
        "row": 6,
        "col": 1
      }
    }
  ]
}