customversion: make script less likely to error in systemd services

patches/customversion/addpatch.py

@@ -1,6 +1,6 @@
 #!/bin/env python3
 import sys
-import os
+import getpass
 import datetime
 import socket
 
@@ -18,8 +18,15 @@ customtext = customtext.strip(",")
 
 timestamp = str(datetime.datetime.utcnow()).split('.')[0] + " UTC"
 
-customtext += ", built on {}@{} at {}".format(os.getlogin(),
-                                              socket.gethostname(),
+try:
+    uname = getpass.getuser()
+except:
+    uname = "unknown"
+
+hostname = socket.gethostname().split(".")[0]
+
+customtext += ", built on {}@{} at {}".format(uname,
+                                              hostname,
                                               timestamp)
 
 # Replace the target string