emacs -Q -nw -batch --eval=3D'(with-temp-buffer (let ((buffer-file-name "/:=
/tmp/x")) (make-auto-save-file-name)))'
Variable binding depth exceeds max-specpdl-size
According to git bisect, the problematic commit is:
commit a1bbc490155b61a634a6d0b165000ce35b93aa35 (HEAD, refs/bisect/bad)
Date: Wed Dec 6 20:49:30 2017 +0100
Fix Bug#29579
* lisp/files.el (file-name-non-special):
Inhibit `file-name-handler-alist' only for some operations.
Add missing operations. (Bug#29579)
[...]
which makes sense because it touches the part of the code that's causing issues.
Since this commit was a bug fix for a related issue with quoted file names, reverting it is probably not the best way forward. We should push a fix and make a new pretest.