Description of problem:

virt-v2v -o rhv-upload fails with:

nbdkit: error: /var/tmp/v2v.t8oS4X/rhv-upload-plugin.py: open: error: ['Traceback (most recent call last):\n', '  File "/var/tmp/v2v.t8oS4X/rhv-upload-plugin.py", line 237, in open\n    cafile = cafile)\n', "NameError: global name 'cafile' is not defined\n"]


This error was fixed upstream in:

commit 7be28a25852ef89a078b4c6e70382fd42bcb2b7e
Author: Nir Soffer <nirsof>
Date:   Fri Dec 7 02:44:21 2018 +0200

    v2v: -o rhv-upload: Fix upload when using https
    
    Fix rhv-cafile option access, broken by commit 6694028f9827 (v2v: -o
    rhv-upload: Only set SSL context for https connections).


The commit introducing this error was backported to the rhel-7.6-lp branch:

commit c1db7d574cf07f47b39ac95a06c9758ac00d7087
Author: Richard W.M. Jones <rjones>
Date:   Wed Sep 19 15:29:13 2018 +0100

    v2v: -o rhv-upload: Only set SSL context for https connections.
    
    For real imageio servers the destination will always be https.  This
    change has no effect there.
    
    However when testing we want to use an http server for simplicity.  As
    there is no certificate or cafile in this case the call to create the
    context will fail.
    
    This also simplifies creation of the context object and recognizes the
    "insecure" flag for connecting to imageio.
    
    Thanks: Nir Soffer.
    (cherry picked from commit 6694028f9827a365385ba3ab199dc3938d8236df)


Version-Release number of selected component (if applicable):
# rpm -q virt-v2v
virt-v2v-1.38.2-12.26.lp.el7ev.x86_64


How reproducible:
Always

Steps to Reproduce:

# cat v2v/upload 
#!/bin/sh

disk=${1:?disk-image required}

virt-v2v \
    -i disk "$disk" \
    -o rhv-upload \
    -oc https://vega10.qa.lab.tlv.redhat.com/ovirt-engine/api \
    -os nsoffer \
    -op /var/tmp/nsoffer/password \
    -of raw \
    -oa preallocated \
    -oo rhv-cafile=/etc/pki/vdsm/certs/cacert.pem \
    -oo rhv-cluster=cluster1 \
    -oo rhv-direct=true

# ./v2v/upload /var/tmp/fedora-27.img
[   0.2] Opening the source -i disk /var/tmp/fedora-27.img
[   0.3] Creating an overlay to protect the source from being modified
[   0.7] Opening the overlay
[   2.1] Inspecting the overlay
[   5.8] Checking for sufficient free disk space in the guest
[   5.8] Estimating space required on target for each disk
[   5.8] Converting Fedora 27 (Twenty Seven) to run on KVM
virt-v2v: warning: /files/boot/grub2/device.map/hd0 references unknown 
device "vda".  You may have to fix this entry manually after conversion.
virt-v2v: This guest has virtio drivers installed.
[  27.1] Mapping filesystem data to avoid copying unused and blank areas
[  27.2] Closing the overlay
[  27.2] Assigning disks to buses
[  27.2] Checking if the guest needs BIOS or UEFI to boot
[  27.2] Initializing the target -o rhv-upload -oa preallocated -oc https://vega10.qa.lab.tlv.redhat.com/ovirt-engine/api -op /var/tmp/nsoffer/password -os nsoffer
[  28.6] Copying disk 1/1 to qemu URI json:{ "file.driver": "nbd", "file.path": "/var/tmp/rhvupload.1uBpHW/nbdkit0.sock", "file.export": "/" } (raw)
nbdkit: error: /var/tmp/v2v.t8oS4X/rhv-upload-plugin.py: open: error: ['Traceback (most recent call last):\n', '  File "/var/tmp/v2v.t8oS4X/rhv-upload-plugin.py", line 237, in open\n    cafile = cafile)\n', "NameError: global name 'cafile' is not defined\n"]
qemu-img: Could not open 'json:{ "file.driver": "nbd", "file.path": "/var/tmp/rhvupload.1uBpHW/nbdkit0.sock", "file.export": "/" }': Failed to read data: Unexpected end-of-file before all bytes were read

virt-v2v: error: qemu-img command failed, see earlier errors

If reporting bugs, run virt-v2v with debugging enabled and include the 
complete output:

  virt-v2v -v -x [...]