Results of testing this locally (the exit value of the last command is
in my prompt):
```
0 $ TRAVIS=true TRAVIS_REPO_SLUG=growstuff/growstuff
TRAVIS_PULL_REQUEST=1007 script/check_contributors_md
Checking to see if you're in CONTRIBUTORS.md...
Thanks for your contribution, ctlewitt!
Please add your name and GitHub handle to the file CONTRIBUTORS.md,
commit it, and update your PR.
1 $ TRAVIS=true TRAVIS_REPO_SLUG=growstuff/growstuff
TRAVIS_PULL_REQUEST=1008 script/check_contributors_md
Checking to see if you're in CONTRIBUTORS.md...
- Miles Gould / [pozorvlak](https://github.com/pozorvlak)
0 $ script/check_contributors_md
Checking to see if you're in CONTRIBUTORS.md...
- Miles Gould / [pozorvlak](https://github.com/pozorvlak)
0 $
```