WhlInstall prints SyntaxError for non-Python .py template during pyc precompilation

[TrapsterDK]

What happened?

With wheel bytecode precompilation enabled, WhlInstall passes the entire installed site-packages tree to compileall. A wheel can legitimately contain non-Python template files whose names end in .py. compileall tries to parse these files and prints a misleading SyntaxError, even though the Bazel action and build succeed.

A real example is pyside6-essentials==6.11.1, which contains this Jinja template:

PySide6/scripts/deploy_lib/android/recipes/PySide6/__init__.tmpl.py

It contains {% for module in qt_modules %}, so it is not valid Python source.

There is no observed runtime impact: the template remains installed and only its .pyc file is absent. The concern is the error-looking diagnostic in otherwise successful builds.

Minimal reproduction

MODULE.bazel:

module(name = "repro")

bazel_dep(name = "aspect_rules_py", version = "2.0.0-alpha.5")

python_interpreters = use_extension(
    "@aspect_rules_py//py:extensions.bzl",
    "python_interpreters",
)
python_interpreters.toolchain(python_version = "3.13")
use_repo(python_interpreters, "python_interpreters")
register_toolchains("@python_interpreters//:all")

uv_bin = use_extension("@aspect_rules_py//uv:extensions.bzl", "uv_bin")
uv_bin.toolchain(version = "0.11.6")
use_repo(uv_bin, "uv")

uv = use_extension("@aspect_rules_py//uv:extensions.bzl", "uv")
uv.declare_hub(hub_name = "pip")
uv.project(
    name = "repro",
    hub_name = "pip",
    lock = "//:uv.lock",
    pyproject = "//:pyproject.toml",
)
use_repo(uv, "pip")

register_toolchains("@uv//:all")

pyproject.toml:

[project]
name = "repro"
version = "0"
requires-python = ">=3.13,<3.14"
dependencies = ["pyside6-essentials==6.11.1"]

Generate uv.lock, then run:

bazel build \
  --@aspect_rules_py//py:python_version=3.13 \
  --@aspect_rules_py//uv/private/pyc:precompile=True \
  --@pip//dep_group=repro \
  @pip//pyside6_essentials

Actual output

INFO: From WhlInstall external/aspect_rules_py++uv+whl_install__repro__pyside6_essentials__6_11_1/actual_install.install:
*** Error compiling '.../site-packages/PySide6/scripts/deploy_lib/android/recipes/PySide6/__init__.tmpl.py'...
  File ".../site-packages/PySide6/scripts/deploy_lib/android/recipes/PySide6/__init__.tmpl.py", line 39
    {% for module in qt_modules %}  # noqa: E999
     ^
SyntaxError: invalid syntax

INFO: Build completed successfully

Expected behavior

Nonfatal per-file bytecode compilation failures should not produce error-looking diagnostics during a successful wheel installation, or there should be a way to suppress them.

The current py/tools/unpack/unpack.py implementation deliberately retains compileall diagnostics while ignoring its aggregate false result. This may conflict with the intent of #1000, which suppressed nonfatal pyc compilation warnings.

Environment

• aspect_rules_py: 2.0.0-alpha.5 (d802a0bc447cb4643a3924a80dd092a412816362)
• Bazel: 9.1.1
• Python: 3.13
• uv: 0.11.6
• Host: Linux x86_64