handle pass through var

Author: blink1073

.evergreen/scripts/setup_tests.py

@@ -171,8 +171,8 @@ def handle_test_env() -> None:
 
     # Handle pass through env vars.
     for var in PASS_THROUGH_ENV:
-        if is_set(var) or getattr(opts, var.lower()):
-            write_env(var, os.environ[var])
+        if is_set(var) or getattr(opts, var.lower(), None):
+            write_env(var, os.environ.get(var, "1"))
 
     if extra := EXTRAS_MAP.get(test_name, ""):
         UV_ARGS.append(f"--extra {extra}")