When restoring a document via revision history, make sure to correctly handle branch logic

What we have decided upon during a meeting is that we want the following behavior:

When restoring a document from version history (which happens  when the user clicks Edit), it replaces the content of the unpublished version of the document branch you are VIEWING. The document you are viewing might NOT be the unpublished version. This means we have the following scenarios:

1) If the document you are viewing is the unpublished. In that case, first the unpublished must be versioned. After that, the restored version its content will replace the unpublished content while keeping the branch info on the unpublished as is.
2) If the document you are viewing is from version history (thus not the unpublished), it depends on the 'to-be-restored' document what needs to be done: If the 'to-be-restored' is for the same branch as the viewed branch, then all that needs to be done is that the 'branchId-unpublished' label in version history is moved to the document that is being restored. If however the document you are viewing is for a different branch, then first that branch needs to be checked out (making it the unpublished), and then step (1) must be executed. This latter use case means that after the restore, the unpublished version has become for the branch

Note that if no branching is used at all, the behavior will be the same as it used to be (before the branch support)