Adding ref-able definitions is a common way of DRYing JSONSchemas. The definitions themselves are not part of the actual schema. Changes to definitions should not cause compatibility problems.

To reproduce:

Remove a field from definitions in e.g. jsonschema/fragment/mediawiki/state/change/page/current.yaml, rematerialize, and run npm test.

2) 1.3.1 must be compatible with 1.3.0

Done is

• jsonschema-tools compatibility tests exclude definitions fields.