Also, what were you hoping to accomplish? At a minimum, are you fixing a bug? Adding a feature? Cleaning up ugly code? Trying to improve performance? Adding comments to something that wasn't obvious?

Did you change an interface that other people use in a way that might break something? Even if it's fixing a bug, is that a bug that other people might have been relying on?

I think the most problematic changes are the little fixes, because often the CL goes from something that looks like it should work, to something else that also looks like it should work. It's very helpful when the commit message describes how it was broken. Otherwise, if you have to roll back the changes you don't know what might get broken again.