Before this patch, we had same code in parthandler for scratchbranchparttype and
processpart where we override bundle2.processpart and add storing changegroup
logic if we get scratchbranchparttype.
Since we have all this logic in parthandler, we can just go ahead and process
the scratchbranchparttype instead of adding it in processparts().
If we delete this code, when does this bundler get processed? I think the purpose of having this serialization logic is so that every other part in the bundle gets processed above first, and then we serialize it here. Without this code here, then the bundler is just thrown away and all the parts that were added to it are lost, and the only serialization ends up being from the scratchbranchparttype processing, which doesn't handle the other parts.
Or am I forgetting something?