pbulk with read-only pkgsrc

Hi,

Just wanted to know of it's still possible to run on pbulk with multiple architectures all using the pkgsrc tree mounted as read only ?

I tried to setup my pbulk this way :

nbqc1-sparc6# nohup sh /usr/pkgsrc/mk/pbulk/pbulk.sh -nlc /srv/pkgsrc/conf/mk.conf.frag &

mk.conf.frag containing this :

nbqc1-sparc6# cat /srv/pkgsrc/conf/mk.conf.frag
PKG_DEVELOPER=yes
MAKE_JOBS=2
SKIP_LICENSE_CHECK=yes
ALLOW_VULNERABLE_PACKAGES=YES
FETCH_USING=fetch
# Can be remote
DISTDIR=/srv/pkgsrc/distfiles
PACKAGES=/srv/pkgsrc/packages
# Must be local

WRKOBJDIR=/var/tmp/pkgbuild

There is some NFS mountpoints :

nbqc1-sparc6# mount | grep nfs
kernfs on /kern type kernfs (local)
nas2:/srv/pkgsrc/pkgsrc2018Q3 on /usr/pkgsrc type nfs (read-only)
nas2:/srv/pbulk/netbsd-8.0/sparc/pkgsrc2018Q3/pbulk on /usr/pbulk type nfs
nas2:/srv/pbulk/netbsd-8.0/sparc/pkgsrc2018Q3/conf on /srv/pkgsrc/conf type nfs
nas2:/srv/pbulk/netbsd-8.0/sparc/pkgsrc2018Q3/packages on /srv/pkgsrc/packages type nfs
nas2:/srv/pbulk/netbsd-8.0/sparc/pkgsrc2018Q3/distfiles on /srv/pkgsrc/distfiles type nfs
nas2:/srv/pbulk/netbsd-8.0/sparc/pkgsrc2018Q3/log on /srv/pkgsrc/log type nfs

I though PACKCAGE variable would overwrite the default location ( /usr/pkgsrc/packages ) but it does not seems to.

nbqc1-sparc6# tail -15 nohup.out
=> Checking file-check results for cwrappers-20180325
=> Creating binary package /tmp/work-pbulk/wrk/pkgtools/cwrappers/work/.packages/cwrappers-20180325.tgz
===> Building binary package for cwrappers-20180325
=> Creating binary package /usr/pkgsrc/packages/All/cwrappers-20180325.tgz
mkdir: /usr/pkgsrc/packages/All: Read-only file system
*** Error code 1

Should I mount my share on /usr/pkgsrc/packages instead of /srv/pkgsrc/packages or relying on PACKAGE variable is the way to go ?

FYI If it might help to understand, for sparc, I have 3-4 pbulk "sparc build host" + 1 "pbulk amd64 master + scan". I have similar setup for vax and pmax. For now all the architecture have a dedicated pkgsrc tree. I just wanted to deduplicate it.