FWIW, I've never heard of this. Ever. And I nosily ask people about their CS programs and careers.
I definitely agree that having a strong github presence is resume-changing. Some employers may ask to see yours even if it's not written explicitly on your resume!
There are two main classes that general software engineering positions seem to "require": data structures and algorithms. That is, the questions from these topics come up regularly and, by definition, will be necessary during your entire software development career. Additionally, it helps to learn about general programming principles / methodologies. I've never been asked to know anything outside of these topics in job interviews. Being good at solving logic puzzles also helps!
Keep in mind, I'm referring to general "software engineer / developer" positions. When you're looking to develop for mobile devices, or for big data companies, or anything else specific, you'll need more specific knowledge. Some people are willing to give you that at the job. Others aren't. But you probably don't want to jump into a job that you aren't very prepared for anyway!
[Again, all of this is based on my own experience and inquiry. Good luck, and enjoy it!! ^^]