Library weak references in blend files

In my .blend files, I’m observing quite a few data blocks of “LibraryWeakReference” type. They seem to be mostly corrupted (a typical data block contains a fragment of a file path that’s broken off in a random place), they remain there even if the blend file is fully self-contained (no external references) and there is no apparent way to purge them, because neither “Purge Unused Data” nor “Clear Data-Block Previews” affect them.
It’s annoying, because these data blocks potentially contain personal data.
I went through the source and the documentation and I can’t tell how these blocks are supposed to work. Are they even supposed to be included in the .blend file?