Before this rev., when a graph view was reloaded (e.g. by clicking
on the graph view switcher), the inital groupby was lost if it
didn't come from the searchview (i.e. if it came from the context
or from the arch). For instance, go to Sales > Reporting > Sales
(the view is grouped by 'date', and there are two groups), reload
by clicking on the graph view switcher: there is only one group
left.
The reload RPC was actually fine. What was wrong is the 'state'
object given to the renderer after the reload, as it didn't contain
the correct groupby, so the view wasn't correctly re-rendered.