CalDAV OPTIONS: do not announce calendar-auto-schedule when CY:scheduling-enabled is F

[dilyanpalauzov]

This way client software can show to the user when server-side scheduling is disabled. The client software can then offer to send iMIP messages.

While _scheduling_enabled() calls

annotatemore_lookupmask_mbox(mailbox, DAV_ANNOT_NS "<" XML_NS_CYRUS ">scheduling-enabled", "", &buf);`

this function executes

annotatemore_lookup_mbe(mbentry, DAV_ANNOT_NS "<" XML_NS_CYRUS ">scheduling-enabled", "", &buf);`

The difference is, that the former also invokes

/* and because of Bron's use of NULL rather than "" at FastMail... */
if (value->len == 0)
    r = _annotate_lookup(mboxname, mboxid, uid, entry, NULL, value);

I do not understand how this NULL is supposed to work at FastMail.