Missing pip dependencies with venvs_site_packages=yes

# 🐞 bug report

### Affected Rule

The issue is caused by the rule: `py_test`

### Is this a regression?

No

### Description

Pip dependencies are missing for py_test targets.
1. Ex: `pytest` pip package depends on `py` pip package. Adding `pytest` to the `deps` for `py_test` doesn't include its transitive dependencies, e.g. `py` (and others). It does include some transitive dependencies though, e.g. `pluggy`
2. In the above example, adding `py` as an explicit dependency in `deps` fixes the problem as it gets included in the generated venv. However, this 'fix' doesn't work for `iniconfig`, another missing transitive dependency of `pytest` - it doesn't get included in the venv

## 🔬 Minimal Reproduction

## 🔥 Exception or Error

Traceback (most recent call last):                                                                                                                                                                                                          

  File "/scratch/nikolay_nikolov/.cache/bazel/_bazel_nikolay_nikolov/79bf5e678fbb2019f1e30944a206f079/sandbox/linux-sandbox/890/execroot/_main/bazel-out/k8-opt/bin/barrel/core/common/logger/logger_tests_py_test.runfiles/_main/barrel/cor

e/common/logger/_logger_tests_py_test_actual_stage2_bootstrap.py", line 537, in                                                                                                                                                     

    main()                                                                                                                                                                                                                                  

  File "/scratch/nikolay_nikolov/.cache/bazel/_bazel_nikolay_nikolov/79bf5e678fbb2019f1e30944a206f079/sandbox/linux-sandbox/890/execroot/_main/bazel-out/k8-opt/bin/barrel/core/common/logger/logger_tests_py_test.runfiles/_main/barrel/cor

e/common/logger/_logger_tests_py_test_actual_stage2_bootstrap.py", line 531, in main                                                                                                                                                        

    _run_py_path(main_filename, args=sys.argv[1:])                                                                                                                                                                                          

  File "/scratch/nikolay_nikolov/.cache/bazel/_bazel_nikolay_nikolov/79bf5e678fbb2019f1e30944a206f079/sandbox/linux-sandbox/890/execroot/_main/bazel-out/k8-opt/bin/barrel/core/common/logger/logger_tests_py_test.runfiles/_main/barrel/cor

e/common/logger/_logger_tests_py_test_actual_stage2_bootstrap.py", line 319, in _run_py_path                                                                                                                                                

    runpy.run_path(main_filename, run_name="__main__")                                                                                                                                                                                      

  File "/scratch/nikolay_nikolov/.cache/bazel/_bazel_nikolay_nikolov/79bf5e678fbb2019f1e30944a206f079/execroot/_main/external/rules_python++python+python_3_10_x86_64-unknown-linux-gnu/lib/python3.10/runpy.py", line 289, in run_path     

    return _run_module_code(code, init_globals, run_name,                                                                                                                                                                                   

  File "/scratch/nikolay_nikolov/.cache/bazel/_bazel_nikolay_nikolov/79bf5e678fbb2019f1e30944a206f079/execroot/_main/external/rules_python++python+python_3_10_x86_64-unknown-linux-gnu/lib/python3.10/runpy.py", line 96, in _run_module_co

de                                                                                                                                                                                                                                          

    _run_code(code, mod_globals, init_globals,                                                                                                                                                                                              

  File "/scratch/nikolay_nikolov/.cache/bazel/_bazel_nikolay_nikolov/79bf5e678fbb2019f1e30944a206f079/execroot/_main/external/rules_python++python+python_3_10_x86_64-unknown-linux-gnu/lib/python3.10/runpy.py", line 86, in _run_code     

    exec(code, run_globals)                                                                                                                                                                                                                 

  File "/scratch/nikolay_nikolov/.cache/bazel/_bazel_nikolay_nikolov/79bf5e678fbb2019f1e30944a206f079/sandbox/linux-sandbox/890/execroot/_main/bazel-out/k8-opt/bin/barrel/core/common/logger/logger_tests_py_test.runfiles/_main/build_supp

ort/python/pytest_proxy.py", line 7, in                                                                                                                                                                                             

    from pytest import console_main                                                                                                                                                                                                         

  File "/scratch/nikolay_nikolov/.cache/bazel/_bazel_nikolay_nikolov/79bf5e678fbb2019f1e30944a206f079/sandbox/linux-sandbox/890/execroot/_main/bazel-out/k8-opt/bin/barrel/core/common/logger/logger_tests_py_test.runfiles/_main/barrel/cor

e/common/logger/_logger_tests_py_test_actual.venv/lib/python3.10/site-packages/pytest/__init__.py", line 6, in                                                                                                                      

    from _pytest.assertion import register_assert_rewrite                                                                                                                                                                                   

  File "/scratch/nikolay_nikolov/.cache/bazel/_bazel_nikolay_nikolov/79bf5e678fbb2019f1e30944a206f079/sandbox/linux-sandbox/890/execroot/_main/bazel-out/k8-opt/bin/barrel/core/common/logger/logger_tests_py_test.runfiles/_main/barrel/cor

e/common/logger/_logger_tests_py_test_actual.venv/lib/python3.10/site-packages/_pytest/assertion/__init__.py", line 9, in                                                                                                           

    from _pytest.assertion import rewrite                                                                                                                                                                                                   

  File "/scratch/nikolay_nikolov/.cache/bazel/_bazel_nikolay_nikolov/79bf5e678fbb2019f1e30944a206f079/sandbox/linux-sandbox/890/execroot/_main/bazel-out/k8-opt/bin/barrel/core/common/logger/logger_tests_py_test.runfiles/_main/barrel/cor

e/common/logger/_logger_tests_py_test_actual.venv/lib/python3.10/site-packages/_pytest/assertion/rewrite.py", line 34, in                                                                                                           

    from _pytest.assertion import util

  File "/scratch/nikolay_nikolov/.cache/bazel/_bazel_nikolay_nikolov/79bf5e678fbb2019f1e30944a206f079/sandbox/linux-sandbox/890/execroot/_main/bazel-out/k8-opt/bin/barrel/core/common/logger/logger_tests_py_test.runfiles/_main/barrel/cor

e/common/logger/_logger_tests_py_test_actual.venv/lib/python3.10/site-packages/_pytest/assertion/util.py", line 19, in 

    from _pytest.config import Config

  File "/scratch/nikolay_nikolov/.cache/bazel/_bazel_nikolay_nikolov/79bf5e678fbb2019f1e30944a206f079/sandbox/linux-sandbox/890/execroot/_main/bazel-out/k8-opt/bin/barrel/core/common/logger/logger_tests_py_test.runfiles/_main/barrel/cor

e/common/logger/_logger_tests_py_test_actual.venv/lib/python3.10/site-packages/_pytest/config/__init__.py", line 45, in 

    from .findpaths import determine_setup

  File "/scratch/nikolay_nikolov/.cache/bazel/_bazel_nikolay_nikolov/79bf5e678fbb2019f1e30944a206f079/sandbox/linux-sandbox/890/execroot/_main/bazel-out/k8-opt/bin/barrel/core/common/logger/logger_tests_py_test.runfiles/_main/barrel/cor

e/common/logger/_logger_tests_py_test_actual.venv/lib/python3.10/site-packages/_pytest/config/findpaths.py", line 12, in 

    import iniconfig

ModuleNotFoundError: No module named 'iniconfig'

## 🌍 Your Environment

**Operating System:**

  

No LSB modules are available.

Distributor ID: Debian

Description:    Debian GNU/Linux 13 (trixie)

Release:        13

Codename:       trixie

  

**Output of `bazel version`:**

  

Build label: 8.3.1

Build target: @@//src/main/java/com/google/devtools/build/lib/bazel:BazelServer

Build time: Mon Jun 30 16:23:40 2025 (1751300620)

Build timestamp: 1751300620

Build timestamp as int: 1751300620

  

**Rules_python version:**

  

1.9.0

  

**Anything else relevant?**

No

Start with the py_test rule and reproduce the logger_tests_py_test failure described in the traceback, using venvs_site_packages=yes. Inspect the generated virtual environment and dependency handling for pytest, py, pluggy, and iniconfig; the issue is done when pytest's required transitive packages are consistently present and the target runs successfully.

Written by the indexing model from the issue text.