From 865af6682c1c244e636588afc1330005dbbd989d Mon Sep 17 00:00:00 2001
From: Kirill Smelkov <kirr@nexedi.com>
Date: Thu, 1 Oct 2020 20:37:04 +0300
Subject: [PATCH] Process pth files even if $PYTHONPATH points to
 site-packages/ (#1960)

---
 docs/changelog/1960.bugfix.rst                |  1 +
 .../via_global_ref/builtin/python2/site.py    |  3 +--
 tests/unit/create/test_creator.py             | 27 +++++++++++++++++++
 3 files changed, 29 insertions(+), 2 deletions(-)
 create mode 100644 docs/changelog/1960.bugfix.rst

diff --git a/docs/changelog/1960.bugfix.rst b/docs/changelog/1960.bugfix.rst
new file mode 100644
index 000000000..fcd217083
--- /dev/null
+++ b/docs/changelog/1960.bugfix.rst
@@ -0,0 +1 @@
+pth files were not processed on CPython2 if $PYTHONPATH was pointing to site-packages/ - by :user:`navytux`. (`#1959 <https://github.com/pypa/virtualenv/issues/1959>`_)
diff --git a/src/virtualenv/create/via_global_ref/builtin/python2/site.py b/src/virtualenv/create/via_global_ref/builtin/python2/site.py
index 366908e77..85eee842a 100644
--- a/src/virtualenv/create/via_global_ref/builtin/python2/site.py
+++ b/src/virtualenv/create/via_global_ref/builtin/python2/site.py
@@ -52,8 +52,7 @@ def load_host_site():
     add_site_dir = sys.modules["site"].addsitedir
     for path in json.loads(site_packages):
         full_path = os.path.abspath(os.path.join(here, path.encode("utf-8")))
-        if full_path not in sys.path:
-            add_site_dir(full_path)
+        add_site_dir(full_path)
 
 
 sep = "\\" if sys.platform == "win32" else "/"  # no os module here yet - poor mans version
diff --git a/tests/unit/create/test_creator.py b/tests/unit/create/test_creator.py
index 68d64b01e..97ab88c84 100644
--- a/tests/unit/create/test_creator.py
+++ b/tests/unit/create/test_creator.py
@@ -579,3 +579,30 @@ def test_no_preimport_threading(tmp_path, no_coverage):
     )
     imported = set(out.splitlines())
     assert "threading" not in imported
+
+
+# verify that .pth files in site-packages/ are always processed even if $PYTHONPATH points to it.
+def test_pth_in_site_vs_PYTHONPATH(tmp_path):
+    session = cli_run([ensure_text(str(tmp_path))])
+    site_packages = str(session.creator.purelib)
+    # install test.pth that sets sys.testpth='ok'
+    with open(os.path.join(site_packages, "test.pth"), "w") as f:
+        f.write('import sys; sys.testpth="ok"\n')
+    # verify that test.pth is activated when interpreter is run
+    out = subprocess.check_output(
+        [str(session.creator.exe), "-c", r"import sys; print(sys.testpth)"],
+        universal_newlines=True,
+    )
+    assert out == "ok\n"
+    # same with $PYTHONPATH pointing to site_packages
+    env = os.environ.copy()
+    path = [site_packages]
+    if "PYTHONPATH" in env:
+        path.append(env["PYTHONPATH"])
+    env["PYTHONPATH"] = os.pathsep.join(path)
+    out = subprocess.check_output(
+        [str(session.creator.exe), "-c", r"import sys; print(sys.testpth)"],
+        universal_newlines=True,
+        env=env,
+    )
+    assert out == "ok\n"