This is one of those problems that I run into infrequently enough that I don't always immediately remember the answer. It usually happens when I'm working on a local topic branch and I try to push it to our staging instance on Heroku.

I push my code as usual, using

git push heroku master

Then I go to test my changes, and wtf? Its like nothing's changed at all. Then I usually try one or more of the follow things:

• Doing a push with the --force option
• Commiting some trivial whitespace-only change
• Attempt to test any model-related changes via the console
• Add a raise "boom" somewhere and commit/push, expecting an exception
• Curse at the computer

Then, at some point, I remember that heroku always commits the master branch. Doh! No wonder I wasn't seeing any of my changes. So I reset head back to somewhere before all of the useless commits of the last 5 minutes, and then push my topic branch like so:

git push heroku branch_name:master

Suddenly everything works as intended and I no longer want to strangle kittens.