commit 0562335908f177c53f0dec307e9414f928a38892
Author: Steve Baker <sbaker@redhat.com>
Date:   Thu Sep 24 11:58:05 2020 +1200

    Fix dhcp_release when client_id is specified
    
    Appending a string to a list results in each character being appended
    as list items, this results in an invalid release command.
    
    This change appends the client_id string to the list instead.
    
    Change-Id: I71a114308e3b68f6daf6e1a202a47b6a453bb81a
    Closes-Bug: #1896850
    (cherry picked from commit 2864957ca53a346418f89cc945bba5cdcf204799)

diff --git a/neutron/privileged/agent/linux/dhcp.py b/neutron/privileged/agent/linux/dhcp.py
index a22e875..9503cf7 100644
--- a/neutron/privileged/agent/linux/dhcp.py
+++ b/neutron/privileged/agent/linux/dhcp.py
@@ -23,7 +23,7 @@ def dhcp_release(interface_name, ip_address, mac_address, client_id,
         cmd += ['ip', 'netns', 'exec', namespace]
     cmd += ['dhcp_release', interface_name, ip_address, mac_address]
     if client_id:
-        cmd += client_id
+        cmd.append(client_id)
     log_errors = processutils.LOG_FINAL_ERROR
     return processutils.execute(*cmd, log_errors=log_errors)