bug#42668: 26.1; Undefined functions when calling invoking project.el

[Eli Zaretskii]

> From: philipk@posteo.net (Philip K.)
> Date: Sun, 02 Aug 2020 11:07:27 +0200
> 
> 
> When trying to to use some project.el commands, and noticed that there
> are a (at least) two undefined functions right after loading project.el
> in a vanilla session:
> 
> - The first complaint is seq-every-p, used by
>   project--read-project-list, but this is "easily" solved by loading
>   seq.el.
> - The more critical complaint is that assoc-delete-all, used by 
>   project--add-to-project-list-front and
>   project--remove-from-project-list are not loaded or defined in Emacs
>   26.
>   My guess is that this function should be replaced by it's functionally
>   equivalent code, that only uses functions available in Emacs 26?

To make sure I understand the report: you are using project.el from
GNU ELPA in conjunction with Emacs 26?