refactor(debug): Exit code 13 is now 4 which had become unused

update-firewall-source.py

@@ -30,7 +30,7 @@ import difflib
 # 1 : Config file invalid, it has no sections
 # 2 : Config file invalid, sections must define at least CONST.CFG_MANDATORY
 # 3 : No physical network device found at "/sys/class/net"
-# 4 : Performing a firewalld rules encountered a FileNotFoundError
+# 4 : Linux find command exited non-zero trying to find a physical network device at "/sys/class/net"
 # 5 : Unable to open firewalld direct rules file for reading
 # 6 : Source and destination are identical when attempting to back up firewalld direct rules file
 # 7 : An option that must have a non-null value is either unset or null
@@ -39,7 +39,6 @@ import difflib
 # 10: Unable to restart systemd firewalld.service unit
 # 11: Unable to add a <rule/> tag to firewalld
 # 12: Kernel sysfs export for network devices at "/sys/class/net" doesn't exist
-# 13: Linux find command exited non-zero trying to find a physical network device at "/sys/class/net"
 
 
 class CONST(object):
@@ -342,8 +341,8 @@ def get_phy_nics() -> list:
                       f"{cpe.cmd}\n"
                       f"Verbatim command output was:\n"
                       f"{cpe.output.rstrip()}\n"
-                      f"Exiting 13 ...")
-            sys.exit(13)
+                      f"Exiting 4 ...")
+            sys.exit(4)
         else:
             if not phy_nics_find.stdout:
                 log.error(f"No physical network device found at {linux_sysfs_nics_abs!r}.\n"