[PATCH v2] emacs: Report a lack of matches when calling `notmuch-show'.

[David Edmondson]

On Wed, Feb 10 2016, David Edmondson wrote:
>> Two minor things, one tiny nit below; and I wonder whether just having
>> the buffer say "No search results" (or something similar) and leave
>> the user to kill it would be nicer than dinging (and more in line with
>> the way search and tree behave).
>>
>> [In some sense I think this way is right and search and tree are wrong,
>> but that is probably difficult to get round as search and tree run
>> asynchronously.]
>
> What if we did "notmuch count $query" first in the search and tree case,
> and did the "(ding) (message ...)" thing if the count returned 0? (Just
> wondering about whether having everything behave that way would be
> possible and acceptable.)

This is pretty easy for `notmuch-search', and "notmuch count $query"
seems very quick. The changes are a bit more involved for `notmuch-tree'.