Extracted from https://github.com/facebook/react/issues/12643.

We're currently diff a host node in the complete phase even if it has bailed out in the begin phase. By itself, this just means we're doing a little bit more work than necessary. But it also has some observable effects. In particular, https://github.com/facebook/react/issues/13424 (which by itself would be very rare and probably not worth fixing) is made worse because we end up committing update to inputs from another component.

I have a fix for this in https://github.com/facebook/react/pull/13423. Filing this for posterity.
ops.push(`Parent:${this.props.step} componentWillUnmount`);
      }
      render() {
        const {step} = this.props;
        return [
          <Child key="a" name={`normal[0]:${step}`} />,
          ReactDOM.createPortal(
            <Child key="b" name={`portal1[0]:${step}`} />,
            portalContainer1,
          ),
          <Child key="c" name={`normal[1]:${step}`} />,
          ReactDOM.createPortal(
            [
              <Child key="d" name={`portal2[0]:${step}`} />,
              <Child key="e" name={`portal2[1]:${step}`} />,
            ],
            portalContainer2,
          ),
        ];
      }
    }
    ReactDOM.render(<Parent step="a" />, container);
    expect(portalContainer1.innerHTML).toBe('<div>portal1[0]:a</div>');
    expect(portalContainer2.innerHTML).toBe(
      '<div>portal2[0]:a</div><div>portal2[1]:a</div>',
    );
    expect(container.innerHTML).toBe(
      '<div>normal[0]:a</div><div>normal[1]:a</div>',