Making a Branch the Master in GIT

git checkout cat_killer
git merge -s ours master
git checkout master
git merge cat_killer
git push

cat_killer is the branch you want to make the master.

Stolen from Stackoverflow post.

no mongrel gem found in sdk rubymine

Even if you are using RVM, Rubymine actually looks at the global installation for the gem. Install thin, mongrel etc on the global Ruby installation that is independent of any gemset.

How to start Thin server on a different port?

thin start -p 80