feat: Allow custom bootstrap template in python_repository

CHANGELOG.md

@@ -88,7 +88,10 @@ A brief description of the categories of changes:
   replacement for the "autodetecting" toolchain.
 * (gazelle) Added new `python_label_convention` and `python_label_normalization` directives. These directive 
   allows altering default Gazelle label format to third-party dependencies useful for re-using Gazelle plugin
-  with other rules, including `rules_pycross`. See [#1939](https://github.com/bazelbuild/rules_python/issues/1939).
+  with other rules, including `rules_pycross`. See [#1939](https://github.com/bazelbuild/rules_python/issues/1939).  
+* (toolchains) `python_register_toolchains` and `python_repository` now accepts `bootstrap_template`
+  and `stage2_bootstrap_template` attributes. These attributes are then passed to the underlying
+  `py_runtime` rule to control the bootstrap template used.
 
 ### Removed
 * (pip): Removes the `entrypoint` macro that was replaced by `py_console_script_binary` in 0.26.0.

python/repositories.bzl

@@ -382,6 +382,8 @@ py_runtime(
     python_version = "PY3",
     implementation_name = 'cpython',
     pyc_tag = "cpython-{interpreter_version_info_major}{interpreter_version_info_minor}",
+    bootstrap_template = {bootstrap_template},
+    stage2_bootstrap_template = {stage2_bootstrap_template},
 )
 
 py_runtime_pair(
@@ -411,6 +413,8 @@ py_exec_tools_toolchain(
         interpreter_version_info_major = python_version_info[0],
         interpreter_version_info_minor = python_version_info[1],
         interpreter_version_info_micro = python_version_info[2],
+        bootstrap_template = repr(str(rctx.attr.bootstrap_template)),
+        stage2_bootstrap_template = repr(str(rctx.attr.stage2_bootstrap_template)),
     )
     rctx.delete("python")
     rctx.symlink(python_bin, "python")
@@ -419,6 +423,7 @@ py_exec_tools_toolchain(
 
     attrs = {
         "auth_patterns": rctx.attr.auth_patterns,
+        "bootstrap_template": rctx.attr.bootstrap_template,
         "coverage_tool": rctx.attr.coverage_tool,
         "distutils": rctx.attr.distutils,
         "distutils_content": rctx.attr.distutils_content,
@@ -430,6 +435,7 @@ py_exec_tools_toolchain(
         "python_version": python_version,
         "release_filename": release_filename,
         "sha256": rctx.attr.sha256,
+        "stage2_bootstrap_template": rctx.attr.stage2_bootstrap_template,
         "strip_prefix": rctx.attr.strip_prefix,
     }
 
@@ -447,6 +453,11 @@ python_repository = repository_rule(
         "auth_patterns": attr.string_dict(
             doc = "Override mapping of hostnames to authorization patterns; mirrors the eponymous attribute from http_archive",
         ),
+        "bootstrap_template": attr.label(
+            default = "//python/private:bootstrap_template",
+            allow_single_file = True,
+            doc = "See the bootstrap_template attribute in the py_runtime rule.",
+        ),
         "coverage_tool": attr.string(
             # Mirrors the definition at
             # https://github.com/bazelbuild/bazel/blob/master/src/main/starlark/builtins_bzl/common/python/py_runtime_rule.bzl
@@ -511,6 +522,11 @@ For more information see the official bazel docs
             doc = "The SHA256 integrity hash for the Python interpreter tarball.",
             mandatory = True,
         ),
+        "stage2_bootstrap_template": attr.label(
+            default = "//python/private:stage2_bootstrap_template",
+            allow_single_file = True,
+            doc = "See the stage2_bootstrap_template attribute in the py_runtime rule.",
+        ),
         "strip_prefix": attr.string(
             doc = "A directory prefix to strip from the extracted files.",
         ),