Make the "completed" status for an upload mean "at least one file in the
upload successfully completed". The "error" status means "all files in
the upload failed".
This means that when an upload has multiple assets and some succeed and
some fail, the whole upload is considered completed. This can happen
when uploading multiple files and some files are over the size limit,
for example. The upload is considered failed only if all files in the
upload fail.
This fixes an issue where, if uploading a single file and that file
failed because it was over the size limit, then the upload wouldn't be
marked as failed.
16b8d4b607