bug#39911: 27.0.90; error in wisent-total-conflicts if no source filename

[Eli Zaretskii <eliz@gnu.org>]

> From: Neil Okamoto <neil.okamoto@gmail.com>
> Date: Wed, 4 Mar 2020 09:23:36 -0800
> 
> This bug was detected while running docker.el and other packages that depend on tablist [1].  Tablist is an
> extension of tabulated-list-mode that provides the ability to filter the tabulated list via an expression language. I
> am not the author of tablist however the author is aware of this issue.
> 
> In 27.0.90, tablist is now giving an error when entering its expression editor.  In the debugger I traced the error
> to wisent-total-conflicts in lisp/cedet/semantic/wisent/comp.el line 2273, in commit
> 390b4bc1e25fe691548d7ec982eb2f7027fe26a3 [2].  That commit introduced a mechanism to ignore
> “expected conflicts” via a symbol whose name is constructed on the fly like this:
> 
>     (format "wisent-%s--expected-conflicts"
>                                      (replace-regexp-in-string "\\.el$" "" src)
> 
> However, this code doesn’t handle the case where the filename “src” is nil.

Thank you for your report.

Lars, could you please look into this?  It's a regression in Emacs 27.