Comment 1 for bug 728138

That sounds useful. Is this the sort of option you'd like to set once in a configuration file? Or would you rather a command line option?

(A command line option is harder, off the top of my head at least 'merge', 'remerge' and 'update' all perform merges, and perhaps there are other commands from plugins that do too. But if that approach suits your use case better let's see if we can find a satisfactory way to do that.)