This script was used in january 2020 to delete all CRAN visits: P585.
This caused some links between origins and snapshots/revisions to be lost, for all packages that had a version removed or were entirely removed from CRAN (see T2536).
It also loses some release history for packages that weren't removed from CRAN (ie. we lost the info they didn't change, or what release they added between visits).
So we should restore these visits from a backup.