rocketchat: File upload chunks may exist without their metadata.
rocketchat: File upload chunks may exist without their metadata.

This is likely an error somewhere in rocketchat's MongoDB "eventual
consistency," but there is no problem with skipping the chunks at this
step.

In the one case where this was observed so far, the upload-id was not
referenced in any message -- if it is referenced and has chunks, but
has no metadata, we will fail later, at that reference.

andersk/zulip,andersk/zulip,rht/zulip,andersk/zulip,zulip/zulip,zulip/zulip,zulip/zulip,zulip/zulip,rht/zulip,zulip/zulip,andersk/zulip,rht/zulip,andersk/zulip,andersk/zulip,rht/zulip,zulip/zulip,rht/zulip,rht/zulip,rht/zulip,andersk/zulip,zulip/zulip