Bug #88537 EF6 Code First + 3-level inheritance + TPT: queries return wrong entity types

Description:
Using code first w/ EF6.1.3 & MySql 5.7, if the model contains a 3-level hierarchy
and the mapping is Table-per-type,
queries return entities with a wrong type, or throw an exception.

e.g.

in Seed():
context.Cats.AddOrUpdate(c => c.Name,
    new Cat { Name = "Chloe", AnimalProperty1 = "female cat",
        CatProperty1 = "Cat3" });
context.Animals.AddOrUpdate(a => a.Name,
    new Cat { Name = "Lucy", AnimalProperty1 = "female cat",
        CatProperty1 = "Cat4" },
etc.

foreach (Animal a in context.Animals) gives
  Animal: 2 - HouseCat - Sophie - female cat - Cat2 - HouseCat2
  Animal: 3 - Dog - Chloe - female cat - 
  Animal: 4 - Dog - Lucy - female cat - 
  Animal: 1 - Dog - Max - male dog - Dog1
  Animal: 5 - Dog - Buddy - male dog - Dog5

context.Animals.First(a => a.Name.StartsWith("B")):
First animal name B: 5 - Dog - Buddy - male dog - Dog5

but

context.Animals.First(a => a.Name.StartsWith("C")):
First animal name C: 3 - Dog - Chloe - female cat -

context.Animals.First(a => a.Name.StartsWith("L")):
First animal name L: 4 - Dog - Lucy - female cat - 

In the example, Chloe and Lucy are clearly cats but the returned entities are of type Dog with empty Dog-specific properties.

As a consequence, context.Cats.First(a => a.Name.StartsWith("L")) throws

System.NotSupportedException: All objects in the EntitySet 'Context.Animals' must have unique primary keys. However, an instance of type 'MySqlInheritanceBug.Entities.HouseCat' and an instance of type 'MySqlInheritanceBug.Entities.Dog' both have the same primary key value, 'EntitySet=Animals;Id=4'.

and so on.

The database tables, their data and the generated SQL all look good.
There is no such problem with TPH but it is not always an option.

How to repeat:
Create a code first model including the following hierarchy:
  abstract class Grandparent {...}
  class Parent1 : Grandparent {...}
  class Parent2 : Grandparent {...}
  class Child11: Parent1 {...}
(Grandparent=Animal, Parent1=Cat, Parent2=Dog, Child11=HouseCat in the example)

Use Table-per-type representation

Seed each type with data

Query the DbSets (using foreach, .First(), etc.)

VS2015 project to demonstrate the bug

Attachment: MySqlInheritanceBug.6.9.9.zip (application/octet-stream, text), 184.83 KiB.

Test output

Attachment: TestResult.txt (text/plain), 1.21 KiB.

Hello Fekete István,

Thank you for the bug report and test case.
Verified this behavior on Visual Studio 2015 with Connector/NET 6.10.4 version.

Thanks,
Chiranjeevi.

Screenshot

Attachment: Bug_88537.png (image/png, text), 177.64 KiB.