Account ID not inserted into contact record

[iscon]

Not sure why nobody recognized that so far: If I select a contact for an account in it's subpanel (select) then a record gets written to account_contact but the account id doesn't get inserted into the contact record. This in turn means that the field "account" in contact doesn't show an entry but "accounts" does.
So although this contact has one account only assigned to it it shows in the so to speak "multi account" field but not in the single one. if I then add a role to this account all of a sudden it shows in both fields.

Solution: Write field account_id in contact when account_contact is written. For clarification purposes rename the field account in contact to "primary_account"

[yuri]

We must write it only if it's empty.

[iscon]

There are two conditions when to write: When the account_contact record is created and contact.account_id is empty. Or if primary account is changed.