React "next" regression

TypeScript Version: 3.2.0-dev.20181106

Code

import React = require("react");
function f<P>(App: React.ComponentClass<P> | React.StatelessComponent<P>): void {
    class C extends React.Component<P & { x: number }> {
        render() {
            return <App {...this.props} />;
        }
    }
}

Expected behavior:

No error, as in ts3.1.

Actual behavior:

src/a.tsx:6:21 - error TS2322: Type 'Readonly<{ children?: ReactNode; }> & Readonly<P & { x: number; }>' is not assignable to type 'IntrinsicAttributes & P & { children?: ReactNode; }'.
  Type 'Readonly<{ children?: ReactNode; }> & Readonly<P & { x: number; }>' is not assignable to type 'P'.

6             return <App {...this.props} />;
                      ~~~


Found 1 error.

Found in next on DefinitelyTyped.