Merge pull request #566 from vyos/mergify/bp/sagitta/pr-565

T6173: fix TypeError: 'NoneType' object is not iterable (backport #565)

scripts/build-vyos-image

@@ -207,7 +207,7 @@ if __name__ == "__main__":
  sys.exit(1)
 
  # Validate characters in version name
- if 'version' in args:
+ if 'version' in args and args['version'] != None:
  allowed = string.ascii_letters + string.digits + '.' + '-' + '+'
  if not set(args['version']) <= set(allowed):
  print(f'Version contained illegal character(s), allowed: {allowed}')