fix(venv): include pth files at the root of the site-packages folder

Before this PR we would not include `pth` files at the root of the
`site-packages` folder, but we would include if they are further down
the tree.

Fixes #3339
Fixes #2071

Author: aignas

CHANGELOG.md

@@ -105,6 +105,9 @@ END_UNRELEASED_TEMPLATE
 * (venvs) {obj}`--venvs_site_packages=yes` works for packages that dynamically
   link to shared libraries
   ([#3228](https://github.com/bazel-contrib/rules_python/issues/3228)).
+* (venvs) {obj}`--venvs_site_packages=yes` includes `pth` files at the root of the
+  site-packages folder
+  ([#3339](https://github.com/bazel-contrib/rules_python/issues/3339)).
 * (uv) {obj}`//python/uv:lock.bzl%lock` now works with a local platform
   runtime.
 * (toolchains) WORKSPACE builds now correctly register musl and freethreaded

python/private/common.bzl

@@ -36,6 +36,7 @@ PYTHON_FILE_EXTENSIONS = [
     "dylib",  # Python C modules, Mac specific
     "py",
     "pyc",
+    "pth",  # import 'pth' files
     "pyi",
     "so",  # Python C modules, usually Linux
 ]

python/private/venv_runfiles.bzl

@@ -290,9 +290,10 @@ def get_venv_symlinks(ctx, files, package, version_str, site_packages_root):
             entry = VenvSymlinkEntry(
                 kind = VenvSymlinkKind.LIB,
                 link_to_path = paths.join(runfiles_dir_name, site_packages_root, filename),
+                link_to_file = src,
                 package = package,
                 version = version_str,
-                venv_path = filename,
+                venv_path = path,
                 files = depset([src]),
             )
             venv_symlinks.append(entry)

tests/venv_site_packages_libs/app_files_building/app_files_building_tests.bzl

@@ -204,6 +204,33 @@ def _test_empty_and_trivial_inputs_impl(env, _):
         VenvSymlinkKind.LIB: {"a": "+pypi_a/site-packages/a"},
     })
 
+def _test_top_level_symlinks(name):
+    analysis_test(
+        name = name,
+        impl = _test_top_level_symlinks_impl,
+        target = "//python:none",
+    )
+
+_tests.append(_test_top_level_symlinks)
+
+def _test_top_level_symlinks_impl(env, _):
+    # Test with empty list of entries
+    actual = build_link_map(_ctx(), [])
+    env.expect.that_dict(actual).contains_exactly({})
+
+    # Test with an entry with no files
+    entries = [
+        _entry("a.py", "+pypi_a/site-packages", ["a.py"]),
+        _entry("a.pth", "+pypi_a/site-packages", ["a.pth"]),
+    ]
+    actual = build_link_map(_ctx(), entries)
+    env.expect.that_dict(actual).contains_exactly({
+        VenvSymlinkKind.LIB: {
+            "a.pth": "+pypi_a/site-packages",
+            "a.py": "+pypi_a/site-packages",
+        },
+    })
+
 def _test_multiple_venv_symlink_kinds(name):
     analysis_test(
         name = name,