Remnants of comment information when module is disabled

To reproduce problem, on a fresh D7 checkout (comment.module 1.828):
- disable comment module
- go to admin/content or node/add/article or node/add/page

You'll get multiple warnings like:

Notice: Undefined index: comment in entity_get_info() (line 6338 of /(path)/includes/common.inc).
Warning: Invalid argument supplied for foreach() in _field_info_prepare_instance() (line 288 of /(path)/modules/field/field.info.inc).

To remove the problem:
- either enable comment.module
- or uninstall it

In both cases, the problem goes away. To reproduce it at will, enable the module then disable it without uninstalling.