I find that github has always had poor to okay search capabilities.
For example, have you ever tried to search for a repo name, only to find 1000 forks? wat. Ever tried to search issues for a specific issue, only to find no results, removing a word or two to get a less accurate search.
Search for me is about discoverability. And github is for developers for the most part.
As a developer I want discoverability for code! I want regex features (like in google code search), better matches. Ways to compress my search results down. Search tags code:'if Awesome()'.
I just feel they could be doing so much better in this area.