Not to worry!

Step 1: Find something that can cut: scissors, knife, I literally hacked at it with a flat-edge screwdriver once.

Step 2: A zipper pull's-length above the zipper stop (where the pull can no longer be pulled down), cut between two teeth on the side of the zipper that the pull is no attached to. You just want a slit, you do not want to cut all the way through the zipper fabric and into the suit.

Step 3: Bring the zipper pull all the way to the bottom of the track.

Step 4: Gently move the pull up, feeding the slit into the top of the zipper pull.

Step 5: Continue zipping up the suit until you have some room below the zipper pull and above the slit you cut.

Step 6: Prevent the zipper from being pulled below the slit again. The best way to do this is by sewing several loops of thread across the closed track just above where you cut. However, a good temporary solution is to slap a patch of duct tape over the slit on both sides of the zipper.

You can also just proceed to rex on without doing Step 6, and complete this step later. The worst that'll happen is when you unzip later you might pull the zipper pull back off the track, but it'll be easy to reseat it again.