[FIX] give the build host Arch's group ids

install: invalid group: '11'

The filesystem package creates directories with `install -g 11`, and
GNU coreutils rejects a gid that resolves to nothing. gid 11 is `ftp`
on Arch; Ubuntu leaves it free.

This is the circular corner of any bootstrap: the package that DEFINES
/etc/group needs groups that do not exist yet. The way out is to give
the build host the target's id map, not to work around the check --
rewriting the install call to force a numeric gid would produce
directories owned by a group the target does not have.

Only the ids Arch uses and Ubuntu lacks are created, and only when
missing, so a host that is already correct is left alone. Checked one
by one: of 1, 2, 10, 11, 12 and 50, only 11 was absent.

--- FR ---

  install: invalid group: '11'

Le paquet filesystem cree des repertoires avec « install -g 11 », et
GNU coreutils refuse un gid qui ne resout vers rien. Le gid 11 est
« ftp » sur Arch ; Ubuntu le laisse libre.

C est le coin circulaire de tout amorcage : le paquet qui DEFINIT
/etc/group reclame des groupes qui n existent pas encore. La sortie est
de donner a l hote de compilation la table d identifiants de la cible,
non de contourner la verification -- forcer l interpretation numerique
produirait des repertoires appartenant a un groupe que la cible n a
pas.

Seuls les identifiants qu Arch utilise et qu Ubuntu n a pas sont crees,
et seulement s ils manquent : un hote deja correct n est pas touche.
Verifie un a un : sur 1, 2, 10, 11, 12 et 50, seul le 11 etait absent.

Assisted-by: Claude Opus 5

scripts/bootstrap-pacman.sh

@@ -74,6 +74,24 @@ configure_makepkg() {
     # pacman refuses to initialise alpm without its database directory. The
     # error is only a warning during packaging, but it hides real ones.
     sudo mkdir -p /var/lib/pacman
+    # Arch's numeric group ids must EXIST on the build host.
+    #
+    # The filesystem package creates directories with `install -g 11`, and
+    # GNU coreutils rejects a gid that resolves to nothing:
+    #
+    #   install: invalid group: '11'
+    #
+    # gid 11 is `ftp` on Arch; Ubuntu leaves it free. This is the circular
+    # corner of any bootstrap -- the package that DEFINES /etc/group needs
+    # groups that do not exist yet -- and the way out is to give the build
+    # host the target's id map rather than to work around the check.
+    #
+    # Only the ids Arch uses and Ubuntu lacks are created, and only when
+    # missing, so an already-correct host is left alone.
+    if ! getent group 11 > /dev/null 2>&1; then
+        sudo groupadd -g 11 ftp
+        echo "created group ftp (gid 11), required by the filesystem package"
+    fi
     # CHOST must be the CANONICAL triplet, not the Debian-style one.
     #
     # gcc -dumpmachine reports s390x-linux-gnu here, but config.sub