Hello Emacs developers,

I found a bug in cl-reduce, which should be reproducible by running the test in the patch. I'm running 26.2 but the bug is also present in master. Please let me know if there are any problems with the patch (including that it is useless :) or if I need to do something else.

Thank you for your hard work maintaining Emacs!

Adrià Garriga-Alonso