From aa9b6f66f0cd207db2822015e7548a04c5824458 Mon Sep 17 00:00:00 2001
From: Tzu-ping Chung <uranusjr@gmail.com>
Date: Sat, 29 Jan 2022 14:07:31 +0800
Subject: [PATCH] Disable location warning for Python < 3.10

---
 src/pip/_internal/locations/__init__.py | 23 +++++++++++++++--------
 1 file changed, 15 insertions(+), 8 deletions(-)

diff --git a/src/pip/_internal/locations/__init__.py b/src/pip/_internal/locations/__init__.py
index 6aeb64e79ec..fb1d7d87a80 100644
--- a/src/pip/_internal/locations/__init__.py
+++ b/src/pip/_internal/locations/__init__.py
@@ -38,30 +38,37 @@
 
 logger = logging.getLogger(__name__)
 
-if os.environ.get("_PIP_LOCATIONS_NO_WARN_ON_MISMATCH"):
-    _MISMATCH_LEVEL = logging.DEBUG
-else:
-    _MISMATCH_LEVEL = logging.WARNING
 
 _PLATLIBDIR: str = getattr(sys, "platlibdir", "lib")
 
+_USE_SYSCONFIG_DEFAULT = sys.version_info >= (3, 10)
+
 
 def _should_use_sysconfig() -> bool:
-    """
-    This function determines the value of _USE_SYSCONFIG.
+    """This function determines the value of _USE_SYSCONFIG.
+
     By default, pip uses sysconfig on Python 3.10+.
     But Python distributors can override this decision by setting:
         sysconfig._PIP_USE_SYSCONFIG = True / False
     Rationale in https://github.com/pypa/pip/issues/10647
+
+    This is a function for testability, but should be constant during any one
+    run.
     """
     if hasattr(sysconfig, "_PIP_USE_SYSCONFIG"):
         return bool(sysconfig._PIP_USE_SYSCONFIG)  # type: ignore [attr-defined]
-    return sys.version_info >= (3, 10)
+    return _USE_SYSCONFIG_DEFAULT
 
 
-# This is a function for testability, but should be constant during any one run.
 _USE_SYSCONFIG = _should_use_sysconfig()
 
+# Be noisy about incompatibilities if this platforms "should" be using
+# sysconfig, but is explicitly opting out and using distutils instead.
+if _USE_SYSCONFIG_DEFAULT and not _USE_SYSCONFIG:
+    _MISMATCH_LEVEL = logging.WARNING
+else:
+    _MISMATCH_LEVEL = logging.DEBUG
+
 
 def _looks_like_bpo_44860() -> bool:
     """The resolution to bpo-44860 will change this incorrect platlib.