* rmurl: Fix a case where removing the last url left git-annex thinking
content was still present in the web special remote.
* SETURLPRESENT, SETURIPRESENT, SETURLMISSING, and SETURIMISSING
used to update the presence information of the external special remote
that called them; this was not documented behavior and is no longer done.
Done by making setUrlPresent and setUrlMissing only update presence info
for the web, and only when the url is a web url. See the comment for
reasoning about why that's the right thing to do.
In AddUrl, had to make it update location tracking, to handle the
non-web-url case.
This commit was sponsored by Ewen McNeill on Patreon.
451171b7c1