From ef35e73a711f980972d1ed5f7514bd816c1ccca5 Mon Sep 17 00:00:00 2001
From: Paul Moore <p.f.moore@gmail.com>
Date: Mon, 5 Apr 2021 15:31:08 +0100
Subject: [PATCH 1/2] Make pip work with warnings converted to errors

---
 src/pip/__main__.py              | 11 +++++++++--
 tests/functional/test_warning.py |  5 +++++
 2 files changed, 14 insertions(+), 2 deletions(-)

diff --git a/src/pip/__main__.py b/src/pip/__main__.py
index 063fd1aacfd..fe34a7b7772 100644
--- a/src/pip/__main__.py
+++ b/src/pip/__main__.py
@@ -1,5 +1,6 @@
 import os
 import sys
+import warnings
 
 # Remove '' and current working directory from the first entry
 # of sys.path, if present to avoid using current directory
@@ -18,7 +19,13 @@
     path = os.path.dirname(os.path.dirname(__file__))
     sys.path.insert(0, path)
 
-from pip._internal.cli.main import main as _main
-
 if __name__ == "__main__":
+    # Work around the error reported in #9540, pending a proper fix.
+    # Note: It is essential the warning filter is set *before* importing
+    #       pip, as the deprecation happens at import time, not runtime.
+    warnings.filterwarnings(
+        "ignore", category=DeprecationWarning, module=".*packaging\\.version"
+    )
+    from pip._internal.cli.main import main as _main
+
     sys.exit(_main())
diff --git a/tests/functional/test_warning.py b/tests/functional/test_warning.py
index 3558704bcef..5c5b1a201ce 100644
--- a/tests/functional/test_warning.py
+++ b/tests/functional/test_warning.py
@@ -42,3 +42,8 @@ def test_version_warning_is_not_shown_if_python_version_is_not_2(script):
 
 def test_flag_does_nothing_if_python_version_is_not_2(script):
     script.pip("list", "--no-python-version-warning")
+
+
+def test_pip_works_with_warnings_as_errors(script):
+    script.environ['PYTHONWARNINGS'] = 'error'
+    script.pip("--version")

From 8d6870aba5241468897fed5cbb109e16ac319b27 Mon Sep 17 00:00:00 2001
From: Paul Moore <p.f.moore@gmail.com>
Date: Mon, 5 Apr 2021 15:35:29 +0100
Subject: [PATCH 2/2] News file

---
 news/9779.bugfix.rst | 1 +
 1 file changed, 1 insertion(+)
 create mode 100644 news/9779.bugfix.rst

diff --git a/news/9779.bugfix.rst b/news/9779.bugfix.rst
new file mode 100644
index 00000000000..2145b641e27
--- /dev/null
+++ b/news/9779.bugfix.rst
@@ -0,0 +1 @@
+Fix pip to work with warnings converted to errors.