Fix missing import in test cases (#792)
diff --git a/tests/site_scons/site_tools/nanopb.py b/tests/site_scons/site_tools/nanopb.py
index 37b8e20..4abf02a 100644
--- a/tests/site_scons/site_tools/nanopb.py
+++ b/tests/site_scons/site_tools/nanopb.py
@@ -34,6 +34,7 @@
 from SCons.Script import Dir, File
 import os.path
 import platform
+import sys
 
 try:
     warningbase = SCons.Warnings.SConsWarning