User-site special case fixes

src/pip/_internal/locations/_distutils.py

@@ -5,7 +5,6 @@
 
 import os
 import os.path
-import sys
 from distutils.cmd import Command as DistutilsCommand
 from distutils.command.install import SCHEME_KEYS
 from distutils.command.install import install as distutils_install_command
@@ -13,26 +12,9 @@ from distutils.sysconfig import get_python_lib
 from typing import Dict, List, Optional, Tuple, Union, cast
 
 from pip._internal.models.scheme import Scheme
-from pip._internal.utils.compat import WINDOWS
 from pip._internal.utils.virtualenv import running_under_virtualenv
 
-from .base import get_major_minor_version, user_site
-
-if WINDOWS:
-    bin_py = os.path.join(sys.prefix, "Scripts")
-    bin_user = os.path.join(user_site, "Scripts")
-    # buildout uses 'bin' on Windows too?
-    if not os.path.exists(bin_py):
-        bin_py = os.path.join(sys.prefix, "bin")
-        bin_user = os.path.join(user_site, "bin")
-else:
-    bin_py = os.path.join(sys.prefix, "bin")
-    bin_user = os.path.join(user_site, "bin")
-
-    # Forcing to use /usr/local/bin for standard macOS framework installs
-    # Also log to ~/Library/Logs/ for use with the Console.app log viewer
-    if sys.platform[:6] == "darwin" and sys.prefix[:16] == "/System/Library/":
-        bin_py = "/usr/local/bin"
+from .base import bin_py, bin_user, get_major_minor_version
 
 
 def _distutils_scheme(

src/pip/_internal/locations/_sysconfig.py

@@ -9,7 +9,7 @@ from pip._internal.exceptions import InvalidSchemeCombination, UserInstallationI
 from pip._internal.models.scheme import SCHEME_KEYS, Scheme
 from pip._internal.utils.virtualenv import running_under_virtualenv
 
-from .base import get_major_minor_version
+from .base import bin_user, get_major_minor_version
 
 logger = logging.getLogger(__name__)
 
@@ -101,12 +101,22 @@ def get_scheme(
 
     paths = sysconfig.get_paths(scheme=scheme_name, vars=variables)
 
-    # Special header path for compatibility to distutils.
+    # Pip historically uses a special header path in virtual environments.
     if running_under_virtualenv():
-        base = variables.get("base", sys.prefix)
+        if user:
+            base = variables.get("userbase", sys.prefix)
+        else:
+            base = variables.get("base", sys.prefix)
         python_xy = f"python{get_major_minor_version()}"
         paths["include"] = os.path.join(base, "include", "site", python_xy)
 
+    # Special user scripts path on Windows for compatibility to distutils.
+    # See ``distutils.commands.install.INSTALL_SCHEMES["nt_user"]["scritps"]``.
+    if scheme_name == "nt_user":
+        base = variables.get("userbase", sys.prefix)
+        python_xy = f"Python{sys.version_info.major}{sys.version_info.minor}"
+        paths["scripts"] = os.path.join(base, python_xy, "Scripts")
+
     scheme = Scheme(
         platlib=paths["platlib"],
         purelib=paths["purelib"],
@@ -131,7 +141,10 @@ def get_bin_prefix():
 
 def get_bin_user():
     # type: () -> str
-    return sysconfig.get_paths(scheme=_infer_scheme("user"))["scripts"]
+    # pip puts the scripts directory in site-packages, not under userbase.
+    # I'm honestly not sure if this is a bug (because ``get_scheme()`` puts it
+    # correctly under userbase), but we need to be compatible.
+    return bin_user
 
 
 def get_purelib():

src/pip/_internal/locations/base.py

@@ -5,6 +5,7 @@ import sysconfig
 import typing
 
 from pip._internal.utils import appdirs
+from pip._internal.utils.compat import WINDOWS
 from pip._internal.utils.virtualenv import running_under_virtualenv
 
 # Application Directories
@@ -46,3 +47,20 @@ try:
     user_site = site.getusersitepackages()  # type: typing.Optional[str]
 except AttributeError:
     user_site = site.USER_SITE
+
+
+if WINDOWS:
+    bin_py = os.path.join(sys.prefix, "Scripts")
+    bin_user = os.path.join(user_site, "Scripts")
+    # buildout uses 'bin' on Windows too?
+    if not os.path.exists(bin_py):
+        bin_py = os.path.join(sys.prefix, "bin")
+        bin_user = os.path.join(user_site, "bin")
+else:
+    bin_py = os.path.join(sys.prefix, "bin")
+    bin_user = os.path.join(user_site, "bin")
+
+    # Forcing to use /usr/local/bin for standard macOS framework installs
+    # Also log to ~/Library/Logs/ for use with the Console.app log viewer
+    if sys.platform[:6] == "darwin" and sys.prefix[:16] == "/System/Library/":
+        bin_py = "/usr/local/bin"