fix: revert the removal and use getattr

Author: aignas

python/private/python_bootstrap_template.txt

@@ -568,6 +568,7 @@ def main():
   print_verbose("VENV_REL_SITE_PACKAGES:", VENV_REL_SITE_PACKAGES)
   print_verbose("WORKSPACE_NAME:", WORKSPACE_NAME )
   print_verbose("bootstrap sys.executable:", sys.executable)
+  print_verbose("bootstrap sys._base_executable:", getattr(sys, "_base_executable", "unknown"))
   print_verbose("bootstrap sys.version:", sys.version)
 
   args = sys.argv[1:]