pushState method works with full URLs only

[ybelenko]

I'm dissapointed with pushState method right now. It says that I can use full urls only.
Let's imagine I have multistep form and I have routes

<Route path="/" component={ App }
    <Route path="companies" companent={ CompanyPage }>
        <Route path="feedback/:stepName" component={ MultiStepForm } />
    </Route>
    <Route path="staff" component={ StaffPage }>
        <Route path="feedback/:stepName" component={ MultiStepForm } />
    </Route>
</Route>

In this scenario when user clicks "continue" button in the form I need to change url from .../feedback/step_one to .../feedback/step_two, but I don't know in which route(companies or staff) user is located.
It would be very convenient to change last part of the url by calling pushState(null, "step_two") instead of parsing and replacing current url manually. If I understand correct, main goal of react-router is to avoid manual URL parsing, so there should be way to change URL partially.

[timdorr]

Dupe of #2172