在运行rake db：migrate之前使用git的最佳方法

I've checked out a new branch to install a gem that I often have various troubles with. The problem is that even though I can destroy this branch, the results of running rake db:migrate are surviving in the database and in db/schema.rb. Since I'm having trouble undoing the database changes, I'm having to scrap the app and then start over. Big time waste.I've checked out a new branch to install a gem