API (relationship, create) of type "Employee of" does not set the employer_id

An API call to create an employment relationship between an Individual and an Organization does not set the 'employer_id' and 'organization_name' columns in the contact table for the employee record.

Reproduced on the demo site using the API explorer. Create an employment relationship, then go on the contact summary for the Individual, the 'Employer' field is empty, but the relationship tab shows that the employment relationship does exist. Tested with start_date and end_date for the relationship not set in the API call.

This seems to be a regression from the 4.2 LTS.