usermod --gid regroups every file under an account's home, and accounts were made
with / as home: they now have /nonexistent, and an older account's home is moved
there (without its files) before its group changes. A sub-path asked for later that
holds data not in the group waits for the operator as the root would. The take act
gives the group to hardlinked files an account owns (the *arr apps' downloads) and
leaves root's; a file's setuid or setgid bit the regroup takes is never put back, so
no setgid file hands out the library's group; each is counted. An apply no longer
waits for a running take walk.
A root in the group with setgid was kept without a warrant even when the data beneath
it was not in the group, which §7 says the operator is asked about. A root is now
kept without asking only when it is empty, or it and a bounded sample beneath it are
all in the group with group write (and setgid on folders). On busybox, an account the
mesh made is given its added groups with addgroup and delgroup; a change of its
primary group is refused, saying why.
jschoubben