The age of a failing test is very useful for tracking changes that caused the bug. The problem with the age value is that the start point of bug lifespan is counted from the latests completed build.
Very often builds fail for that or another reason (build icon is grey) which resets all the ages.

My proposal is to make the age function ignore faulty and interrupted builds and continue incrementing ages with every completed build.

It will look like

build 1 (completed) - age 1
build 2 (completed) - age 2
build 3 (failed, slave ran out of memory) - age is still 2
build 4 (completed) - age 3.
build 5 (interrupted) - age is still 3.
build 6 (completed) - age 4.

It does not sound difficult to fix. Unfortunately the only way that I found to fix this is to contribute to jenkins code and re-compile it for our environment. Am I right about that or there's a shorter path?