bug#7530: describe-function etc. should remember locations from $HOME too

[Chong Yidong]

jidanni@jidanni.org writes:

> We do
> (describe-function (quote gnus-summary-w3m-safe-toggle-inline-images))
> and see
>     gnus-summary-w3m-safe-toggle-inline-images is an interactive compiled
>     Lisp function.
>
> And wonder "why does it usually say what file it is in, but not today?"
>
> Well that is because it was in
> ~/.emacs-w3m.elc
> ~/.emacs-w3m

Please provide a minimal recipe for reproducing this bug, including a
minimal .emacs file.