I tried implementing fast_finish=true in my project by following the official blog instructions. Here is my .travis.yml file.
There are 6 total jobs; 4 primary jobs and 2 optional jobs, which are allowed to fail. When I submit a commit or a PR, I expect the result to pass (a tick mark to appear) as soon as my primary jobs complete. But, currently, I have to wait till at least 1 of the optional jobs complete.
The dirty workaround is to add an optional job that just runs true script to overcome this.