p9 synced folder is readonly when it shouldn't be

[matutter]

Describe the bug

I have a p9 synced_folder that should be writable from the guest however it is readonly.

To Reproduce

1. Install the latest provider.

gem fetch vagrant-libvirt --version 0.12.2
vagrant plugin install vagrant-libvirt-0.12.2.gem

2. vagrant up --no-provision
3. vagrant ssh
4. cd releases
5. touch asd.txt (fails - read only file system)

Use this vagrant file:

Expected behavior
The folder /home/vagrant/releases should be writable inside the guest.

Screenshots

Versions (please complete the following information)::

• Libvirt version: 8.0.0
• Vagrant version [output of vagrant version]: 2.2.19
• Vagrant flavour [Upstream or Distro]: Distro 2.2.19+dfsg-1ubuntu1
• Vagrant plugins versions (including vagrant-libvirt) [output of vagrant plugin list]:

vagrant-libvirt (0.12.2, global)
  - Version Constraint: 0.12.2

Debug Log

Command: VAGRANT_LOG=debug vagrant up --no-provision --provider=libvirt >vagrant.log 2>&1

vagrant.log

A Vagrantfile to reproduce the issue:

# Using NFS requires elevated privileges on the host machine, p9 may have
# permission issues when attempting to write from the guest to the host.
use_nfs = false

Vagrant.configure("2") do |config|
    config.vm.box = "generic/ubuntu2004"
    config.vm.hostname = "ubuntu"

    config.vm.provider :libvirt do |domain|
        domain.uri = 'qemu+unix:///system'
        domain.driver = 'kvm'
        domain.cpus = 4
        domain.memory = 8192
        domain.graphics_type = "none"
    end

    if use_nfs
        config.vm.synced_folder "./releases", "/home/vagrant/releases",
            type: "nfs",
            nfs_udp: false,
            nfs_version: 4
    else
        config.vm.synced_folder "./releases", "/home/vagrant/releases",
            type: "9p",
            disabled: false,
            accessmode: "mapped",
            readonly: false,
            access: "1000",
            mount: true
    end

    config.vm.provision "shell",
        path: "bootstrap.sh",
        privileged: false,
        keep_color: false

end