Is the idea to eliminate any "stress risers" in the cut edge? This isn't likely to help. It would be better to chamfer and polish the edges of the holes... not so easy on the inner aspect.

EDIT: Here's an example of chamfering a hole to minimize stress risers. The chamfering on the inside was done with an "inverted cone" bur in a Dremel tool.


These chamfered stress-breaker holes successfully stopped the progression of cracks for several thousands of miles.