Severity icons aren't easy to recognize

You are currently using the same icon, a warning icon with different colors, for the 3 lowest levels of severity (low, medium and high), and a different one for those with critical severity, a flame (which I think is awesome)

This implementation makes the user have to remember what each color on the 3 lower levels mean instead of recognizing it just by looking at them.

This, I think, violates Jacob Nielsen's usability heuristic #6 Recognition rather than recall. This would be solved by using different icons (not just colors) for each level

Being the first time that I'm working with the new version (which I'm loving so far) I have to use tooltips to check on each bug's severity, taking me a lot of time.