Don't overwrite passed props to mapDispatchToProps with the default

[oskarhane]

I found an unexpected behavior when defining second argument received by mapDispatchToProps to have a default value.
The default value is always passed to it, even though other props are defined on the component.

I created a test to demonstrate it: oskarhane@b0a2b89

If the default is removed:
let mapDispatchToProps = (d, p = {}) => { to
let mapDispatchToProps = (d, p) => {
it works as expected.

[developit]

I'm trying to figure out what could cause this, no luck so far.