So I apologize in advance if I didn't follow the processes exactly, I was going to attempt to review this to move it along, but ran into issues applying the patch cleanly to master. I fixed the issues I was having applying it, and created a new patch (attached).
Managed to test it out after I got it applied, and it is working as expected for exclusion constraints, as well as normal indexes.
This test was performed on Windows 10 (64 bit), and Postgres was compiled using MSYS2.
