Unable to do mixin with private property

[unional]

TypeScript Version:
1.8.7

Code

// A self-contained demonstration of the problem follows...
class A {
  public propA; any = {};
  private propB: number = 1;
}

class B implements A {
  public propA: any;
  private propB: number;  // here
}
applyMixin(A, [B]);

Expected behavior:
Compile success

Actual behavior:
Compile failed.
When private propB: number; exists, tsc failed with:

error TS2420: Class 'A' incorrectly implements interface 'B'.
  Types have separate declarations of a private property 'propB'.`

When private propB: number; is removed, tsc failed with:

error TS2420: Class 'A' incorrectly implements interface 'B'.
  Property 'propB' is missing in Type 'A'.

[RyanCavanaugh]

Duplicate #3854

[unional]

@RyanCavanaugh , thanks. Feel free to close this as dup. 🍺