The burn_in_tests.py script runs its queries against the Evergreen API using the mongodb-mongo-master as its project. If we change it to interpolate the Evergreen project name using branch_name, then we wouldn't need to update the script each time we branch (SERVER-27119).

Additionally, the burn_in_tests.py script uses @{upstream} to get the merge-base commit of the current commit and the latest commit of the associated branch. However, the git.get_project command doesn't configure the environment to have a branch that tracks the remote (EVG-1327).

1. We should run git branch --force ${branch_name} origin/${branch_name} prior to invoking the burn_in_tests.py script to create the branch and have it track the remote. The --force option is suggested to avoid having the eventual completion of EVG-1327 cause a task to fail as a result of the branch already existing.
2. We should always specify the --branch=${branch_name} option to the burn_in_tests.py script in the etc/evergreen.yml project configuration.