Multiple copies of a single attachment accumulate in a lists archive.

This is not Bug #266749. It is a different issue.

After multiple fixes, we have arrived at the current situation wherein if there is a message in a list's digest.mbox which throws an exception in digest processing, the exception is logged and processing aborted. This normally results in the missing digests being noticed and investigated, the log messages being found, the problem message in the digest.mbox fixed or removed, and normal digest processing being resumed.

If however, the list allows attachments which are scrubbed from the plain digest, the processing of the digest will store all attachments from messages prior to the one causing the exception. On a busy list, there can be many digests triggered by size before the problem is discovered and each attempt at producing a digest results in the same set of attachments being scrubbed and stored again in the archive potentially wasting much space.