If this is the wrong list to send this to, my apologies, please let me know
where to go.
I've used nxml-mode for a long time. When typing in an xml attribute and using completion,
emacs would respond by completing the attribute and also adding =" to allow me to
immediately type the value of the xml attribute. I recently upgraded to emacs 26, and it now
only completes the attribute hame. The original completion behavior (adding =") is
described in the manual at
<https://www.gnu.org/software/emacs/manual/html_node/nxml-mode/Completion.html> .