It appears that delete will return nonzero even on failure (NOT_FOUND server response). This appears to violate the api description that says "@return: Nonzero on success." The memecached text protocol defines only 'DELETED' as "success", and 'NOT_FOUND' to indicate the server did not have the key at the time the delete was requested -- and records this in server stats as 'delete_misses'.

The fix is trivial (simply remove NOT_FOUND from the expect list for delete), and I was going to just open a pull req for it, but there appears to be some history behind the decision.

It appears this change was part of 81933bc and related to an old-bug (at least this is the bug referenced in the commit).

Is there historical/deeper meaning surrounding this change?
Is it a bug or just a kludge to maintain some pre-existing behavior (e.g. api stability)?