* lisp/minibuffer.el (completion--capf-wrapper): Check applicability before

* lisp/minibuffer.el (completion--capf-wrapper): Check applicability before
retuning non-nil for non-exclusive completion data.
* lisp/progmodes/etags.el (tags-completion-at-point-function):
* lisp/info-look.el (info-lookup-completions-at-point): Mark as non-exclusive.
(info-complete): Adjust accordingly.
* lisp/erc/erc-pcomplete.el (erc-pcompletions-at-point): Mark the completion
data as non-exclusive if it's using the default-completion-function.
(pcomplete-erc-parse-arguments): Rename pcomplete-parse-erc-arguments.
(pcomplete-erc-setup): Use new name.