Incorrect error when assigning to omitted and extended record type

TypeScript Version:
typescript@3.2.0-dev.20181011
typescript@3.1.3
typescript@3.0.3

Search Terms:

Code

type Baa = { a: number, b: number };
type Omit<T, K> = Pick<T, Exclude<keyof T, K>>;

function foo<P extends Baa>() {
    const foo: { foo: string } & Omit<P, 'b'> = null as any;
    const props: Baa = foo;
}

Expected behavior:

No error.

Actual behavior:

test.ts:6:11 - error TS2322: Type '{ foo: string; } & Pick<P, Exclude<keyof P, "b">>' is not assignable to type 'Baa'.
  Property 'a' is missing in type '{ foo: string; } & Pick<P, Exclude<keyof P, "b">>'.

6     const props: Baa = foo;
            ~~~~~

Removing the { foo: string } & works.
Removing the Omit works.
Removing the P and using Baa directly works.

Playground Link:

https://agentcooper.github.io/typescript-play/?ts=2.9.1#code/C4TwDgpgBAQghnKBeKBvKcBcUB2BXAWwCMIAnAGiiIH5t9iyoBfAbgChRIoB5AgS2AAeACqUA0gD5kUAAp8AxgGsRlAKIAPeQBs8AEwiDFEEAHsAZlFFRJE9mzN4c84HxM4oZkycEyoEdcAQOLoAzrAIEgAUAJRobFAJUPJuIcAeXtjonibYqaR8OADmzFAAZDz8QjKUAORENVIo+FpaGGFwOCDsiUkpaWCkJmAh2PCIKNnsTGxAA

Related Issues:

Fixed by #29121.

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Incorrect error when assigning to omitted and extended record type #27883

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Incorrect error when assigning to omitted and extended record type #27883

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ahejlsberg commented on Feb 1, 2019

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