a hub track, which is somebody else's instruction
  under /gbdb, no such file          /gbdb/hg38/noSuchDataVersion.txt   opened it, and there was no such file
  a file outside /gbdb               /etc/passwd                        refused, the path came back unread
  climbing out of /gbdb              /gbdb/hg38/../../etc/passwd        refused, the path came back unread
  a prefix that only looks right     /gbdbNot/hg38/x.txt                refused, the path came back unread
  not a path at all                  v27 2026-01-01                     refused, the path came back unread

a native track, which is ours
  no such file                       /no/such/dir/version.txt           opened it, and there was no such file
  not a path at all                  v27 2026-01-01                     refused, the path came back unread

