How to push different local Git branches to Heroku/master

Heroku has a policy of ignoring all branches but 'master'. While I'm sure Heroku's designers have excellent reasons for this policy (I'm guessing for storage and performance optimization), the consequence to me as a developer is that whatever local topic branch I may be working on, I would like an easy way to switch Heroku's master to that local topic branch and do a "git push heroku -f" to over-w