Victor said in bug 812869 comment 12: "One problem, unrelated to this patch, is that I can't seem to be able to place a breakpoint inside an eval block, not even while it is being evaluated. This also seemed to have regressed recently, although I can't seem to pinpoint a changeset range. Another (possibly related) confusing behavior with eval blocks: go to our beloved debugger page, set a breakpoint on line 14, click me and start stepping in; it seems we're going through the block twice."

Even though eval isn't commonly used without dynamically generated code, I have already started looking into this. Taking.

I haven't actually been looking into this for quite a while.