Comment 2 for bug 1862417

Version is 19.4-33-gbb4131a2-0ubuntu1~18.04.1 from Ubuntu Bionic.

The full log is as follows:

2020-02-07 21:00:18,780 - cc_disk_setup.py[DEBUG]: Creating new filesystem.
2020-02-07 21:00:18,780 - util.py[DEBUG]: Running command ['udevadm', 'settle'] with allowed return codes [0] (shell=False, capture=True)
2020-02-07 21:00:18,798 - cc_disk_setup.py[DEBUG]: Checking /dev/xvdg against default devices
2020-02-07 21:00:18,798 - cc_disk_setup.py[DEBUG]: Identifying device to create swap filesytem on
2020-02-07 21:00:18,798 - util.py[DEBUG]: Running command ['/bin/lsblk', '--pairs', '--output', 'NAME,TYPE,FSTYPE,LABEL', '/dev/xvdg'] with allowed return codes [0] (shel
l=False, capture=True)
2020-02-07 21:00:18,802 - cc_disk_setup.py[DEBUG]: Automatic device for /dev/xvdg identified as /dev/xvdg
2020-02-07 21:00:18,802 - cc_disk_setup.py[DEBUG]: File system type 'swap' with label 'swap' will be created on /dev/xvdg
2020-02-07 21:00:18,803 - util.py[DEBUG]: Running command ['/bin/lsblk', '--pairs', '--output', 'NAME,TYPE,FSTYPE,LABEL', '/dev/xvdg', '--nodeps'] with allowed return cod
es [0] (shell=False, capture=True)
2020-02-07 21:00:18,806 - cc_disk_setup.py[WARNING]: Force flag for swap is unknown.
2020-02-07 21:00:18,806 - cc_disk_setup.py[DEBUG]: Creating file system swap on /dev/xvdg
2020-02-07 21:00:18,806 - cc_disk_setup.py[DEBUG]: Using cmd: ['/sbin/mkswap', '/dev/xvdg', '-L', 'swap', '']
2020-02-07 21:00:18,806 - util.py[DEBUG]: Running command ['/sbin/mkswap', '/dev/xvdg', '-L', 'swap', ''] with allowed return codes [0] (shell=False, capture=True)
2020-02-07 21:00:18,817 - util.py[DEBUG]: Creating fs for /dev/xvdg took 0.037 seconds
2020-02-07 21:00:18,817 - util.py[WARNING]: Failed during filesystem operation
Failed to exec of '['/sbin/mkswap', '/dev/xvdg', '-L', 'swap', '']':
Unexpected error while running command.
Command: ['/sbin/mkswap', '/dev/xvdg', '-L', 'swap', '']
Exit code: 1
Reason: -
Stdout:
Stderr: mkswap: invalid block count argument: ''
2020-02-07 21:00:18,822 - util.py[DEBUG]: Failed during filesystem operation
Failed to exec of '['/sbin/mkswap', '/dev/xvdg', '-L', 'swap', '']':
Unexpected error while running command.
Command: ['/sbin/mkswap', '/dev/xvdg', '-L', 'swap', '']
Exit code: 1
Reason: -
Stdout:
Stderr: mkswap: invalid block count argument: ''
Traceback (most recent call last):
  File "/usr/lib/python3/dist-packages/cloudinit/config/cc_disk_setup.py", line 994, in mkfs
    util.subp(fs_cmd, shell=shell)
  File "/usr/lib/python3/dist-packages/cloudinit/util.py", line 2065, in subp
    cmd=args)
cloudinit.util.ProcessExecutionError: Unexpected error while running command.
Command: ['/sbin/mkswap', '/dev/xvdg', '-L', 'swap', '']
Exit code: 1
Reason: -
Stdout:
Stderr: mkswap: invalid block count argument: ''