don't install GRUB on Pearl Rolltide 7.0

[Hortencio]

Where I install a copy on disk "Apague o disco e instale o PEARL 7.0 ROLLTIDE", a instalação não grava o GRUB e falha.

ProblemType: Bug
DistroRelease: Pearl 7.0
Package: ubiquity 18.09.9+pearl7
ProcVersionSignature: Ubuntu 4.15.0-22.24-generic 4.15.17
Uname: Linux 4.15.0-22-generic x86_64
ApportVersion: 2.20.9-0ubuntu7
Architecture: amd64
CasperVersion: 1.394
Date: Wed Nov 14 06:37:19 2018
InstallCmdLine: BOOT_IMAGE=/casper/vmlinuz file=/cdrom/preseed/custom.seed boot=casper iso-scan/filename= only-ubiquity quiet splash --
LiveMediaBuild: PearlDesktop 7.0 - Release amd64
ProcEnviron:
 LANGUAGE=pt_BR.UTF-8
 PATH=(custom, no user)
 XDG_RUNTIME_DIR=<set>
 LANG=pt_BR.UTF-8
 LC_NUMERIC=C.UTF-8
SourcePackage: ubiquity
UpgradeStatus: No upgrade log present (probably fresh install)