fix import logic for adding files to customs. Current logic throws exeption when trying to append to customs list because Import function has no return.

SConstruct

@@ -20,11 +20,13 @@ except:
 env.PrependENVPath("PATH", os.getenv("PATH"))
 
 # Custom options and profile flags.
-customs = ["custom.py"]
+
 try:
-    customs += Import("customs")
+    Import("customs")
 except:
-    pass
+    customs = []
+customs += ["custom.py"]
+
 profile = ARGUMENTS.get("profile", "")
 if profile:
     if os.path.isfile(profile):