handle windows case of using --python_path

Author: rickeylev

python/private/py_executable.bzl

@@ -777,6 +777,12 @@ def _create_stage1_bootstrap(
 
     python_binary_actual = venv.interpreter_actual_path if venv else ""
 
+    # Runtime may be None on Windows due to the --python_path flag.
+    if runtime and runtime.supports_build_time_venv:
+        resolve_python_binary_at_runtime = "0"
+    else:
+        resolve_python_binary_at_runtime = "1"
+
     subs = {
         "%interpreter_args%": "\n".join([
             '"{}"'.format(v)
@@ -786,7 +792,7 @@ def _create_stage1_bootstrap(
         "%python_binary%": python_binary_path,
         "%python_binary_actual%": python_binary_actual,
         "%recreate_venv_at_runtime%": str(int(venv.recreate_venv_at_runtime)) if venv else "0",
-        "%resolve_python_binary_at_runtime%": "0" if runtime.supports_build_time_venv else "1",
+        "%resolve_python_binary_at_runtime%": resolve_python_binary_at_runtime,
         "%target%": str(ctx.label),
         "%venv_rel_site_packages%": venv.venv_site_packages if venv else "",
         "%workspace_name%": ctx.workspace_name,