All except very simple changes to the code base should have an associated JIRA issue with the proposed patch for peer review.
After the review create a branch for it off of master and apply the patch:
git checkout -b CRUNCH-42 git am --signoff path/to/CRUNCH-42-Change.patch
Check if everything applies cleanly and look over the changes. Run the test suite (unit tests or integration tests depending on the extent of the changes). If everything passes:
git checkout master git merge CRUNCH-41 git push -u origin master
Then set the JIRA status to Resolved.