Detect Changes - Incorrect State

[avinash-phaniraj-readify]

Scenario -

1. Attach an entity to the context with a known primary key specified (Id > 0)
2. Extend entity graph by adding/associating another entity with an Id > 0
3. Trigger DetectChanges for ex; invoke context.ChangeTracker.Entries().

You will find the new entity (which was not explicitly attached) being tracked.
It's state however is incorrectly tracked as "Added" and not "Unchanged".

If the new entity were to be attached via context.Attach, its state is correctly determined.

Steps to reproduce

Repro : https://github.com/avinash-phaniraj-readify/EFCoreTestBed/tree/DetectChangesStateError

           var context = new TestDbContext(options);

            var emp = new Employee { Id = 1, Name = "known employee" };
            emp.Devices = new List<EmployeeDevice>();
            context.Attach(emp);

            var device = new EmployeeDevice { Id = 1, EmployeeId = 1, Device = "known device" };

            emp.Devices.Add(device);
            context.ChangeTracker.Entries();

            Debug.Assert(context.Entry(device).State == EntityState.Unchanged);

Further technical details

EF Core version: 2.1.4
Database Provider: EntityFrameworkCore.SqlServerCompact35 2.1.2.1
Operating system: Win 10
IDE: (e.g. Visual Studio 2017 15.8.4)

[ajcvickers]

@avinash-phaniraj-readify Please see my response to #13564 and also see #13575 which would change this if we chose to implement it.