[PATCH v4 2/3] emacs: `notmuch-show-buttonize-links' only `notmuch-show's a message if it exists

[Mark Walters]

> * emacs/notmuch-show.el (notmuch-show-if-found): new function that only shows
>   a message/thread if present in the database and otherwise returns an error.

I like this in principle but it interacts awkwardly with the automatic tag
exclusion. If the id:<message-id> matches a message with an excluded tag
then notmuch-show-if-found will not let you view it, but if you typed the
same search in a search field it would show you the message. 

Note notmuch show currently does not currently respect excluded tags (see
id:"871uqvgrnm.fsf at qmul.ac.uk"), and this is not completely trivial to
fix since it is not clear quite what its behaviour should be in some
corner cases.

Perhaps we could have an option like "--include-all" to notmuch
search/count to tell it not to apply the exclusions. On the other hand
that might also be useful as something the user can type in a search box
so a special search term (eg include:all) might be better.

Best wishes

Mark