Looking at the postmortem[1], it looks like the patches provided were not good enough in the developer's eyes:
I believed it held mutable aliasing invariant and I was very happy that someone found real problem. I wanted to solve the problem, just with a bit of creativity. And use RefCell solution only if it would be not possible to solve it with any other way. Btw, I like the solution I found, it is in master and solves the problem at least one from the issue. If you want to push boundaries you have to touch this boundaries and sometimes you push too hard.
That sounds very much like the developer was headed to fixing them, but I guess the harassment and need for now won.