v2.4.6: Workaround for SBCL bug on ARM64
I ran into a bug in SBCL 2.6.5 that causes an FSet function to miscompile on ARM64 (Apple M), causing it to go into an infinite loop. (It's an internal function invoked by doing with on a dynamic tuple; if you use tuples and run on Mac, you will likely be affected.) This release contains a workaround. The SBCL fix is already in the pipeline, and will presumably be included in 2.6.7.