We got a testproject and hold the node, on the mount image step, after we kill the mount image proccess, after run the mount image manually, we got this output:

[zuul@node-0003003071 ~]$ umount /tmp/tmp.s6qdHltSvU
umount: /tmp/tmp.s6qdHltSvU: must be superuser to unmount.
[zuul@node-0003003071 ~]$ sudo umount /tmp/tmp.s6qdHltSvU
umount: /tmp/tmp.s6qdHltSvU: target is busy.
[zuul@node-0003003071 ~]$ sudo tripleo-mount-image -a /home/zuul/overcloud-hardened-uefi-full.raw -m /tmp/tmp.s6qdHltSvb
mountpoint: /tmp/tmp.s6qdHltSvb: No such file or directory
+ qemu-img info --output json /home/zuul/overcloud-hardened-uefi-full.raw
+ grep '"format": "raw"'
    "format": "raw",
+ image_format='--format raw'
+ qemu-nbd --format raw --connect /dev/nbd4 /home/zuul/overcloud-hardened-uefi-full.raw
+ vgscan
  WARNING: Not using device /dev/nbd1p4 for PV t9T6FU-lPQj-YkLM-Nsps-PAQr-xY4s-cCmijh.
  WARNING: Not using device /dev/nbd2p4 for PV t9T6FU-lPQj-YkLM-Nsps-PAQr-xY4s-cCmijh.
  WARNING: Not using device /dev/nbd3p4 for PV t9T6FU-lPQj-YkLM-Nsps-PAQr-xY4s-cCmijh.
  WARNING: Not using device /dev/nbd4p4 for PV t9T6FU-lPQj-YkLM-Nsps-PAQr-xY4s-cCmijh.
  WARNING: PV t9T6FU-lPQj-YkLM-Nsps-PAQr-xY4s-cCmijh prefers device /dev/nbd0p4 because device is used by LV.
  WARNING: PV t9T6FU-lPQj-YkLM-Nsps-PAQr-xY4s-cCmijh prefers device /dev/nbd0p4 because device is used by LV.
  WARNING: PV t9T6FU-lPQj-YkLM-Nsps-PAQr-xY4s-cCmijh prefers device /dev/nbd0p4 because device is used by LV.
  WARNING: PV t9T6FU-lPQj-YkLM-Nsps-PAQr-xY4s-cCmijh prefers device /dev/nbd0p4 because device is used by LV.
  Found volume group "vg" using metadata type lvm2
+ vgchange --refresh
  WARNING: Not using device /dev/nbd1p4 for PV t9T6FU-lPQj-YkLM-Nsps-PAQr-xY4s-cCmijh.
  WARNING: Not using device /dev/nbd2p4 for PV t9T6FU-lPQj-YkLM-Nsps-PAQr-xY4s-cCmijh.
  WARNING: Not using device /dev/nbd3p4 for PV t9T6FU-lPQj-YkLM-Nsps-PAQr-xY4s-cCmijh.
  WARNING: Not using device /dev/nbd4p4 for PV t9T6FU-lPQj-YkLM-Nsps-PAQr-xY4s-cCmijh.
  WARNING: PV t9T6FU-lPQj-YkLM-Nsps-PAQr-xY4s-cCmijh prefers device /dev/nbd0p4 because device is used by LV.
  WARNING: PV t9T6FU-lPQj-YkLM-Nsps-PAQr-xY4s-cCmijh prefers device /dev/nbd0p4 because device is used by LV.
  WARNING: PV t9T6FU-lPQj-YkLM-Nsps-PAQr-xY4s-cCmijh prefers device /dev/nbd0p4 because device is used by LV.
  WARNING: PV t9T6FU-lPQj-YkLM-Nsps-PAQr-xY4s-cCmijh prefers device /dev/nbd0p4 because device is used by LV.
+ vgchange -ay
  WARNING: Not using device /dev/nbd1p4 for PV t9T6FU-lPQj-YkLM-Nsps-PAQr-xY4s-cCmijh.
  WARNING: Not using device /dev/nbd2p4 for PV t9T6FU-lPQj-YkLM-Nsps-PAQr-xY4s-cCmijh.
  WARNING: Not using device /dev/nbd3p4 for PV t9T6FU-lPQj-YkLM-Nsps-PAQr-xY4s-cCmijh.
  WARNING: Not using device /dev/nbd4p4 for PV t9T6FU-lPQj-YkLM-Nsps-PAQr-xY4s-cCmijh.
  WARNING: PV t9T6FU-lPQj-YkLM-Nsps-PAQr-xY4s-cCmijh prefers device /dev/nbd0p4 because device is used by LV.
  WARNING: PV t9T6FU-lPQj-YkLM-Nsps-PAQr-xY4s-cCmijh prefers device /dev/nbd0p4 because device is used by LV.
  WARNING: PV t9T6FU-lPQj-YkLM-Nsps-PAQr-xY4s-cCmijh prefers device /dev/nbd0p4 because device is used by LV.
  WARNING: PV t9T6FU-lPQj-YkLM-Nsps-PAQr-xY4s-cCmijh prefers device /dev/nbd0p4 because device is used by LV.
  Cannot activate LVs in VG vg while PVs appear on duplicate devices.
  Cannot activate LVs in VG vg while PVs appear on duplicate devices.
  Cannot activate LVs in VG vg while PVs appear on duplicate devices.
  Cannot activate LVs in VG vg while PVs appear on duplicate devices.
  Cannot activate LVs in VG vg while PVs appear on duplicate devices.
  Cannot activate LVs in VG vg while PVs appear on duplicate devices.
  Cannot activate LVs in VG vg while PVs appear on duplicate devices.
  Cannot activate LVs in VG vg while PVs appear on duplicate devices.
  8 logical volume(s) in volume group "vg" now active

although it does finishes and doesn't seems to be blocking anything