Fix build warning on Windows
diff --git a/tests/SConstruct b/tests/SConstruct
index 76dab5b..5961f84 100644
--- a/tests/SConstruct
+++ b/tests/SConstruct
@@ -207,5 +207,6 @@
 
 for subdir in Glob('*/SConscript') + Glob('regression/*/SConscript'):
     if str(subdir).startswith("common/"): continue
+    if str(subdir).startswith("common\\"): continue
     SConscript(subdir, exports = 'env', variant_dir = env['VARIANT_DIR'] + '/' + os.path.dirname(str(subdir)))