Import overwrites primary location of contact if use update with Id

If we use update mode using contact Id or External Identifier, It overwrites primary location.

Steps to replicate
1. There is a contact with location of type home and set as primary.
2. Import this contact in update mode with as Internal contact Id : (matching CiviCRM field) or External Identifier : (matching CiviCRM field) and billing location.
3. After import , it makes billing location as Primary location.

Expected behavior : It should add only billing location until and unless contact doesn't have any primary location set.