Allow (or check if possible) replan on virtual package
Doing replan on specially immediate one on virtual package turns out to be pretty useful. The point is that you can just line all package you want to update once before you reexecute updater without needing to select one of them to be the root of three and inserting others as additional dependencies. The reason is that might not be always possible such as if that creates cycle that just can't be broken. With such cycle updater possibly won't allow update as updater is critical package.
I am convince that using virtual packages do not work at the moment with replan as those are ignored when plan is created. This means that with routine cutting away plan in case of replan won't cut it simply because there is not package to cat plan at.