Code review comment for lp://qastaging/~sil2100/ubuntu-release-upgrader/snap-size-estimation

Looking at DistUpgradeQuirks.py's run function we can see that there are currently 6 different quirk handlers that are supported. Is there a reason you didn't use an existing one and created "PreCalcDistUpgrade"? If there is a good reason then I think PreCalcDistUpgrade should be documented with the other ones.