Disable bootstrap for recipes.py invocations in autoroll

recipe_engine/autoroll.py

Index: recipe_engine/autoroll.py
diff --git a/recipe_engine/autoroll.py b/recipe_engine/autoroll.py
index 448c91efc109a97de939012b5167e35ff7167f31..8cb70106a7c56db17fbc178761c6ec0545285349 100644
--- a/recipe_engine/autoroll.py
+++ b/recipe_engine/autoroll.py
@@ -108,6 +108,8 @@ def fetch(repo_root, package_spec):
   args = [
     sys.executable,
     os.path.join(repo_root, package_spec.recipes_path, 'recipes.py'),
+    # Invoked recipes.py should not re-bootstrap (to avoid issues on bots).
+    '--disable-bootstrap',
     'fetch',
   ]
   subprocess.check_call(args)
@@ -126,6 +128,8 @@ def run_simulation_test(repo_root, package_spec, additional_args=None,
   args = [
     sys.executable,
     os.path.join(repo_root, package_spec.recipes_path, 'recipes.py'),
+    # Invoked recipes.py should not re-bootstrap (to avoid issues on bots).
+    '--disable-bootstrap',
   ]
   if not allow_fetch:
     args.append('--no-fetch')