Make sure the current etag is always used ahead of any schedule-etags in a pre-condition check.
Make sure the current etag is always used ahead of any schedule-etags in a pre-condition check.

git-svn-id: 81e381228600e5752b80483efd2b45b26c451ea2@7270 e27351fd-9f3e-4f54-a53b-843176b1656c

trevor/calendarserver,trevor/calendarserver,trevor/calendarserver