In 2.5.6, the progress bar (green coloring from left to right) in the task bar icon correctly accounts for 2-pass processing, meaning it grows during the first pass, reaching 50% half the icon at the end of the first pass. In 2.6.11b160215 and 2.6.8, the bar doesn't do anything on pass 1 when it should go from 0-50%, and goes from 0-100% only on the second pass when it should go from 50-100%.
Due to a huge developer(s) time shortage, not all the nitpicking would/could be handled
As I'm only a user, I can't speak for the developer(s) and you can still hope: sometime, maybe ...