They need to build an original portfolio after hacker school. W see many people who have their hacker school projects, then no commits or no new projects afterwards. The things that catch our eye are when they have a github projects in something that interested them and they built from scratch in python (i.e. not forks or templates). It gives us a chance to review their chops and shows they know how things work.
NOTE: if it's a project that they did at hacker school, we assume that they got hand-held through it and didn't retain much, so those projects are skipped.
For example, one applicant had https://github.com/Eunoia/snakes_on_a_train, which is basically what got them the interview.