The packager tool sometimes generates invalid documents

I noticed once that one XE XAR file contained an invalid Stats.Referrers XML file, which caused the import to fail for that archive. Invalid means that it was truncated at some point. Rebuilding the XE XAR solved the problem, so it seems that it is random and unlikely to happen, since most of the time the build works fine.

Could there be an unflushed stream? I didn't know that this could cause a problem...