Build XCP-ng ISO - issue at create-installimg

[Vagrantin]

Hi everyone,

I'm playing around with the build of the XCP-ng ISO to add a custom RPM in it.
Also, I'm facing an issue where I can't find my way out.

This is the create-installimg.sh step where setup_yum_repos ( from misc.sh ) doesn't manage to access the yum config.

What is weird is that just before this function is called I manage with a simple cat command to access it.
And as per my understanding at reading the script the TPMDIR is set by misc.sh so I don't have control over it.

This is the output of my tests currently.

sudo docker run --rm -it -v "$(pwd)/create-install-image:/create-install-image:ro" -v "$(pwd):/output" b292e8a21068 /bin/bash
[root@85b20fccb0e7 /]# /create-install-image/scripts/create-installimg.sh --output /output/install-8.3.img 8.3
-----Set REPOS-----
YUMCONF: //tmpdir-VcYHGW/yum-171swX.conf
YUMREPOSD: //tmpdir-VcYHGW/yum-repos-eg1dEe.d
YUMCONF_TPML: /create-install-image/configs/8.3/yum.conf.tmpl
ROOTFS: //tmpdir-VcYHGW/rootfs-1RKWIe
YUMFLAGS: --config=//tmpdir-VcYHGW/yum-171swX.conf --installroot=//tmpdir-VcYHGW/rootfs-1RKWIe -q
ls REPOSD
cat YUMCONF
[main]
keepcache=1
debuglevel=2
reposdir=//tmpdir-VcYHGW/yum-repos-eg1dEe.d
logfile=/var/log/yum.log
retries=20
obsoletes=1
gpgcheck=1
assumeyes=1
syslog_ident=mock
syslog_device=
metadata_expire=0
mdpolicy=group:primary
best=1
protected_packages=
skip_missing_names_on_install=0
tsflags=nodocs
--- ISSUE happens here *setup_yum_repos* ----
CRITICAL:yum.cli:Config error: Error accessing file for config file:////tmpdir-VcYHGW/yum-171swX.conf

This is the docker image I'm using.

sudo docker images
                                                                                                                                                                                           i Info →   U  In Use
IMAGE                                 ID             DISK USAGE   CONTENT SIZE   EXTRA
ghcr.io/xcp-ng/xcp-ng-build-env:8.3   b292e8a21068        543MB             0B        

I have been building this from the xcp-ng build env repo:
https://github.com/xcp-ng/create-install-image/tree/master

I'm puzzle and can't find what I'm doing wrong here.

Any hint will be much welcome !