prism-auto bug fix (crashes when run on a single model in build mode).

git-svn-id: https://www.prismmodelchecker.org/svn/prism/prism/trunk@10491 bbc10eb1-c90d-0410-af57-cb519fbb1720

prism/etc/scripts/prism-auto

@@ -225,6 +225,8 @@ def renameExports(prefix, args):
         return arg.startswith("-export")
     if args:
         return [args[0]] + [prependToFile(prefix, args[i+1]) if isExportArg(args[i]) else args[i+1] for i in range(len(args)-1)]
+    else:
+        return args
 
 # Find all files that match any -export switch file argument
 # This takes into account that a .all extension corresponds to five different files