Pull them! It appears our La Nina spring has affected many plantings. As a side note; I never plant sets; always 'plants' or direct seeding.

If you are growing from sets you are growing a plant that has already bulbed but might still be immature enough to be tricked into forming a larger bulb instead of going to seed. Which does not always work because of all of the variables - the handling of the bulbs, timing, weather...
When you first see the flower stalk they are still good as green onions - so planting sets is not a total waste if you can be flexible. I would definately do what rain150 said and pull them - they are spent.

Best of luck!

Just wanted to add that when I pulled my bolted sets there was a mushy layer that I just pulled off in the sink when cleaning them (it made it easy to clean them up). So there might be something usable on yours.

Caramelize 'em in a pan & freeze in small amounts for later. Yum!

Corrine