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Changes between Version 1 and Version 3 of Ticket #28438

-              v1
+              v3
 - this does not happen if the mixin class extends {{{models.Model}}} to begin with.
 - if model extends a mixin that extends {{{object}}}, it ends up in model's {{{bases}}}, however if mixin extends {{{model.Model}}} it does not.
+- when mixin's base class changes, schema migration does not reflect this change in model's {{{bases}}}
 Tested with Django 1.11.3, Python 2.7
+Proposed solution:
+migration should not create database fields for model fields not explicitly listed in {{{fields}}}