netcli operation hangs on uniq

Using netcli to add VLANs to a lagg resulted in a hang.

control-T showed "uniq" to tbe the process waiting.

SSH to same controller hung on DNS lookup. (Evidence: controller was pingable, and DNS lookup eventually timed out and password prompt appeared.)

Suspect this line in netcli is the cause:

p1 = subprocess.Popen("sockstat -46P tcp |awk '{ if ($2 == \"nginx\" && $7 == \":\") print $5\",\"$6 }'|sort|uniq", shell=True, stdout=subprocess.PIPE, encoding='utf8')