Can't read the linked article. Did the study look further into the gender bias assumptions beyond the simple female vs male statistic (e.g by anonymizing code submissions)?
The general tone of this recent article on HN [1] I think was quite negative towards the OP, more so than the median. I have seen similar behavior in code and architecture reviews, interviews, etc for women at companies I have worked. Everything literally turns into a qual. Everything they do is judged to much higher standard. Or even non-sensical standard. It is still the case, that when I come across a woman in dev, she is most likely a freak'n bad ass and has a really thick skin. To me, this shows that we have not yet achieved equality, otherwise there would be more _average_ programmers who are women.
Then there was a second cover-your-ass study by Facebook HR that found that if you adjust gender by seniority/rank the bias went away. This raised the question of why female engineers were at lower ranks after the same amount of time on staff. It might be explained by prior work experience, or starting rank, but it might not be. From the articles on this it looks like they (fb) don't actually want to answer this question.
And there could be many reasons for that, beyond just the simplistic "girls are bad at code." Maybe Facebook has a lower bar for hiring female engineers due to affirmative action.