Description of problem:
RuntimeError: direct upload to host not supported

Version-Release number of selected component (if applicable):
libvirt-4.5.0-28.el7.x86_64
qemu-kvm-rhev-2.12.0-38.el7.x86_64
libguestfs-1.40.2-8.el7.x86_64
virt-v2v-1.40.2-8.el7.x86_64
nbdkit-1.8.0-3.el7.x86_64
nbdkit-1.8.0-3.el7.x86_64
nbdkit-plugin-vddk-1.8.0-3.el7.x86_64
nbdkit-plugin-python2-1.8.0-3.el7.x86_64
nbdkit-plugin-python-common-1.8.0-3.el7.x86_64

ovirt:
ovirt-engine-4.3.6.5-0.1.el7.noarch
ovirt-imageio-proxy-1.5.2-0.el7ev.noarch

ovirt node:
vdsm-4.30.33-1.el7ev.x86_64
ovirt-imageio-daemon-1.5.2-0.el7ev.noarch

How reproducible:
Hardly reproduce.

Steps to Reproduce:
The problem occurs when doing rhv-upload by v2v and '-oo rhv-direct' must be given.

e.x.
virt-v2v  -i ova  -ic qemu:///system -o rhv-upload -os nfs_data -of raw -b ovirtmgmt -n ovirtmgmt /home/ova-images/esx-rhel6-ova.tar -on ova_vm_wxq -oc https://xxxx/ovirt-engine/api -op /tmp/rhv_upload_passwd_file -oo rhv-cafile=/tmp/rhv_upload_ca.pem -oo rhv-cluster=NFS -oo rhv-direct 

Actual results:
libguestfs: trace: disk_has_backing_file = 1qemu-img 'convert' '-p' '-n' '-f' 'qcow2' '-O' 'raw' '/var/tmp/v2vovl62e909.qcow2' 'json:{ "file.driver": "nbd", "file.path": "/var/tmp/rhvupload.Yo89gB/nbdkit0.sock", "file.export": "/" }'nbdkit: debug: accepted connectionnbdkit: python[1]: debug: newstyle negotiation: flags: global 0x3nbdkit: python[1]: debug: newstyle negotiation: client flags: 0x3nbdkit: python[1]: debug: newstyle negotiation: NBD_OPT_GO: client requested export '/' (ignored)nbdkit: python[1]: debug: python: open readonly=0disk.id = 'a806db7c-3d12-4c05-a782-606b4e555e98'cannot read /etc/vdsm/vdsm.id, using any host: [Errno 2] No such file or directory: '/etc/vdsm/vdsm.id'transfer.id = 'd5d227d2-0120-4fea-9af2-12b65e879096'nbdkit: python[1]: error: /var/tmp/v2v.uUtxcu/rhv-upload-plugin.py: open: error: ['Traceback (most recent call last):
', '  File "/var/tmp/v2v.uUtxcu/rhv-upload-plugin.py", line 227, in open
    raise RuntimeError("direct upload to host not supported, "
', 'RuntimeError: direct upload to host not supported, requires ovirt-engine >= 4.2 and only works when virt-v2v is run within the oVirt/RHV environment, eg. on an oVirt node.
']qemu-img: Could not open 'json:{ "file.driver": "nbd", "file.path": "/var/tmp/rhvupload.Yo89gB/nbdkit0.sock", "file.export": "/" }': Failed to read option reply: Unexpected end-of-file before all bytes were readvirt-v2v: error: qemu-img command failed, see earlier errorsrm -rf '/var/tmp/ova.qkrqDn'rm -rf '/var/tmp/v2v.TgrfFV'rm -rf '/var/tmp/v2v.uUtxcu'rm -rf '/var/tmp/v2v.X7bQJ2'rm -rf '/var/tmp/rhvupload.Yo89gB'rm -rf '/var/tmp/null.3m4uO9'libguestfs: trace: closelibguestfs: closing guestfs handle 0x55cb9e38d0f0 (state 0)nbdkit: debug: python: unload

Expected results:
v2v should run successfully.

Additional info:
https://www.redhat.com/archives/libguestfs/2019-November/msg00319.html