Empty Current Employer profile field disables employer relationship AND doesn't prefill on event registration form

When a profile field is left empty by either an anonymous user or a user filling in the form for 'another contact', any existing value for this form should be left unchanged.

If 'Current Employer' field is included in online event registration profile - this behavior works as expected for anonymous (not logged in) user. However, if a logged in user selects 'Register a different person' (cid=0) - then there are 2 bugs:

1. If user selects a contact from the select2 combobox - if the selected contact has a current employer the field is not pre-filled.

2. If does NOT select from combobox - but enters a contact w/ name and email matching an existing contact - and leaves the current employer field empty - then the existing current employer relationship for the matched contact is disabled (should be left unchanged).