<phst@a.muc.corp.google.com> schrieb am Mi., 24. Jan. 2018 um 23:23 Uhr:

>
> 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)
Author: Michael Albinus <michael.albinus@gmx.de>
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.