You're not wrong, and it's not limited to bioinformatics; Reinhart-Rogoff's findings were reversed when an additional 5 rows were included in a spreadsheet they used to calculate their correlation between GDP growth and debt ratios. And of course, they insist that despite the actual outcome being twice as strong and in the opposite direction, they still support their original position.
I wonder if one can get a CS PhD by producing enough retractions. Of course, it won't win you many friends in the academy, and would probably lead to less source code made available. But given the Perl code I've seen published who's termination condition is a divide-by-zero exception, one can argue that peer review in the information age has to include code review.