Context is   bug 903523 

I reverted the offending CL, but I also reverted the roll into tools/build which contained that CL. The recipe roller dutifully noticed that there was a trivial roll it could perform containing the bad CL, and re-landed the roll I had reverted, before landing my revert of the original CL.

I'm not exactly sure what the right solution is to the situation I was in. Should I have not touched the roll? Manually reverted? Manually rolled after the revert of the problematic CL landed?

I also think we should document this in the description of a recipe roll CL.