Hero Availability for Clan War Attacks During Upgrade

It is a known fact that Hero levels are taken into consideration during Clan War match-making. As a result any player upgrading his/her heroes during an ongoing clan war is at a big disadvantage for the war attack. The higher the Hero levels the bigger the disadvantage (as will be matched against better opponent). It might be a good idea to have the heroes available just for making the Clan War attack even during a upgrade (just like they are available for base defense in the war map). This would not discourage people from upgrading heroes just before or during a war.