First render - unneccasary history.pushState

[tomatau]

On first page render, if redux DebugPanel is displayed, the simple router calls history.pushState with the existing route. This means that Router.createElement is invoked twice on ReactRouter - which isn't necessary.

The redux DevTools or perhaps LogMonitor seems to trigger the store.subrscribe callback on an interval. Here, RSR is finding that lastChangeId !== routing.changeId; and so calling the new pushState.

It could be worth caching the routePath and checking for a difference with the current getState().routing.path before invoking updatePath, but of course, that wouldn't take into account any route state changes.

It may be more simple to initialise the lastChangeId to the same value as initialState.changeId - again, there's probably a use case in here somewhere that route.state updates on initial render wouldn't be taken into account...

Perhaps #50 could prevent the unnecessary pushState call on initial render.

[jlongster]

We cannot diff paths, that's what we used to do and it is not reliable at all. In fact we want to call into the router for every single URL change -- even if it's the same URL!

But I think you might be right about initializing the lastChangeId. Let's merge this with #50.