Comment 1 for bug 1815592

I'd like to know if we're actually using the olddirs functionality right now, other than for removing old releases. Once we know that, I would propose using only st.st_mtime for the timestamp check. Checksums only care about the *contents* of the image, not the metadata. Move and link operations will only touch the st_ctime timestamp, so it would allow re-using the checksums in cases of image moves. Also, image moves and hard-links should be fairly safe.

I'll prepare a PR but leave it open for discussion.