Leapp upgrade from RHEL7 to RHEL8 fails with internal repository mirror

Issue

Running leapp preupgrade --no-rhsm --enablerepo rhel-8-for-x86_64-baseos-rpms --enablerepo rhel-8-for-x86_64-appstream-rpms throw the following error:

022-09-01 16:24:30.708586 [ERROR] Actor: target_userspace_creator
Message: Unable to install RHEL 8 userspace packages.
Summary:
    Details: Command ['systemd-nspawn', '--register=no', '--quiet', '-D', '/var/lib/leapp/scratch/mounts/root_/system_overlay', '--setenv=LEAPP_UPGRADE_PATH_TARGET_RELEASE=8.6', '--setenv=LEAPP_NO_RHSM=1', '--setenv=LEAPP_EXPERIMENTAL=0', '--setenv=LEAPP_UPGRADE_PATH_FLAVOUR=default', '--setenv=LEAPP_COMMON_TOOLS=:/etc/leapp/repos.d/system_upgrade/el7toel8/tools', '--setenv=LEAPP_COMMON_FILES=:/etc/leapp/repos.d/system_upgrade/common/files:/etc/leapp/repos.d/system_upgrade/el7toel8/files', '--setenv=LEAPP_ENABLE_REPOS=rhel-8-for-x86_64-baseos-rpms,rhel-8-for-x86_64-appstream-rpms', '--setenv=LEAPP_IPU_IN_PROGRESS=7to8', '--setenv=LEAPP_UNSUPPORTED=0', '--setenv=LEAPP_EXECUTION_ID=xxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxxx', '--setenv=LEAPP_HOSTNAME=foo.example.com', 'dnf', 'install', '-y', '--nogpgcheck', '--setopt=module_platform_id=platform:el8', '--setopt=keepcache=1', '--releasever', u'8.6', '--installroot', '/el8target', '--disablerepo', '*', '--enablerepo', u'rhel-8-for-x86_64-baseos-rpms', '--enablerepo', u'rhel-8-for-x86_64-appstream-rpms', 'dnf', 'dnf-command(config-manager)', '--disableplugin', 'subscription-manager'] failed with exit code 1.
    Stderr: Failed to create directory /var/lib/leapp/scratch/mounts/root_/system_overlay//sys/fs/selinux: Read-only file system
            Failed to create directory /var/lib/leapp/scratch/mounts/root_/system_overlay//sys/fs/selinux: Read-only file system
            Host and machine ids are equal (xxxxxxxxxxxxxxxxxxxxxx): refusing to link journals
            Failed to synchronize cache for repo 'rhel-8-for-x86_64-appstream-rpms', ignoring this repo.
            Failed to synchronize cache for repo 'rhel-8-for-x86_64-baseos-rpms', ignoring this repo.
            Error: Unable to find a match: dnf dnf-command(config-manager)