I believe you already can't change your capital during war.
This is not true at all. You can change your capital any time you hold a city other than your capital.
Logged
Timothy Collett
"The only thing you can't trade for your heart's desire...is your heart." "You are what you do. Choose again, and change." "One of these days, someone's gonna plug you, and you're going to die saying, 'What did I say? What did I say?'" ~ Miles Naismith Vorkosigan
