refactor(python2/site): do not override PYTHONPATH

Author: jd

docs/changelog/1673.bugfix.rst

@@ -0,0 +1 @@
+Fix ``PYTHONPATH`` being overriden on Python 2 — by :user:`jd`.

src/virtualenv/create/via_global_ref/builtin/python2/site.py

@@ -89,19 +89,25 @@ def rewrite_standard_library_sys_path():
         skip_rewrite = value == exe_dir  # don't fix the current executable location, notably on Windows this gets added
         skip_rewrite = skip_rewrite  # ___SKIP_REWRITE____
         if not skip_rewrite:
-            if dir_starts_with(value, exe_dir):
-                # content inside the exe folder needs to remap to original executables folder
-                orig_exe_folder = base_executable[: base_executable.rfind(sep)]
-                value = "{}{}".format(orig_exe_folder, value[len(exe_dir) :])
-            elif dir_starts_with(value, prefix):
-                value = "{}{}".format(base_prefix, value[len(prefix) :])
-            elif dir_starts_with(value, exec_prefix):
-                value = "{}{}".format(base_exec_prefix, value[len(exec_prefix) :])
-            sys.path[at] = value
+            sys.path[at] = translate_directory(
+                value, base_executable, exe_dir, exec_prefix, base_prefix, prefix, base_exec_prefix
+            )
 
+    # Now that we can access os.environ["PYTHONPATH"], we can revert our
+    # rewrite of thoses paths done above
+    import os
 
-def dir_starts_with(directory, prefix):
-    return directory == prefix or directory.startswith(prefix + sep)
+    python_paths = os.environ.get("PYTHONPATH", "").split(":")
+    for ppath in map(abs_path, python_paths):
+        translated_ppath = translate_directory(
+            ppath, base_executable, exe_dir, exec_prefix, base_prefix, prefix, base_exec_prefix
+        )
+        try:
+            at = sys.path.index(translated_ppath)
+        except ValueError:
+            pass
+        else:
+            sys.path[at] = ppath
 
 
 def abs_path(value):
@@ -118,6 +124,22 @@ def abs_path(value):
     return value
 
 
+def translate_directory(directory, base_executable, exe_dir, exec_prefix, base_prefix, prefix, base_exec_prefix):
+    if dir_starts_with(directory, exe_dir):
+        # content inside the exe folder needs to remap to original executables folder
+        orig_exe_folder = base_executable[: base_executable.rfind(sep)]
+        return "{}{}".format(orig_exe_folder, directory[len(exe_dir) :])
+    elif dir_starts_with(directory, prefix):
+        return "{}{}".format(base_prefix, directory[len(prefix) :])
+    elif dir_starts_with(directory, exec_prefix):
+        return "{}{}".format(base_exec_prefix, directory[len(exec_prefix) :])
+    return directory
+
+
+def dir_starts_with(directory, prefix):
+    return directory == prefix or directory.startswith(prefix + sep)
+
+
 def disable_user_site_package():
     """Flip the switch on enable user site package"""
     # sys.flags is a c-extension type, so we cannot monkeypatch it, replace it with a python class to flip it

tests/unit/create/test_creator.py

@@ -23,7 +23,7 @@
 from virtualenv.pyenv_cfg import PyEnvCfg
 from virtualenv.run import cli_run, session_via_cli
 from virtualenv.util.path import Path
-from virtualenv.util.six import ensure_text
+from virtualenv.util.six import ensure_text, ensure_str
 
 CURRENT = PythonInfo.current_system()
 
@@ -111,7 +111,7 @@ def system(session_app_data):
         )
     ],
 )
-def test_create_no_seed(python, creator, isolated, system, coverage_env, special_name_dir, method):
+def test_create_no_seed(python, creator, isolated, system, coverage_env, special_name_dir, method, override_env_var):
     dest = special_name_dir
     cmd = [
         "-v",
@@ -128,6 +128,9 @@ def test_create_no_seed(python, creator, isolated, system, coverage_env, special
     ]
     if isolated == "global":
         cmd.append("--system-site-packages")
+    # Set a path that is inside the virtualenv
+    python_path = dest / "foobar"
+    override_env_var("PYTHONPATH", ensure_str(str(python_path)))
     result = cli_run(cmd)
     coverage_env()
     if IS_PYPY:
@@ -141,6 +144,8 @@ def test_create_no_seed(python, creator, isolated, system, coverage_env, special
     assert not content, "\n".join(ensure_text(str(i)) for i in content)
     assert result.creator.env_name == ensure_text(dest.name)
     debug = result.creator.debug
+    # Check the PYTHONPATH has not been modified
+    assert ensure_text(str(python_path)) in debug["sys"]["path"]
     sys_path = cleanup_sys_path(debug["sys"]["path"])
     system_sys_path = cleanup_sys_path(system["sys"]["path"])
     our_paths = set(sys_path) - set(system_sys_path)