From 03d0e2f6c4e9f335b941e2155ffcd1b6836058dc Mon Sep 17 00:00:00 2001
From: Krzysztof Konopko <kkonopko@users.noreply.github.com>
Date: Mon, 15 Jun 2020 19:28:46 +0200
Subject: [PATCH] bpo-40448: ensurepip: Do not use cache (GH-19812)

ensurepip optionally installs or upgrades 'pip' and 'setuptools' using
the version of those modules bundled with Python.  The internal PIP
installation routine by default temporarily uses its cache, if it
exists.  This is undesirable as Python builds and installations may be
independent of the user running the build, whilst PIP cache location
is dependent on the user's environment and outside of the build
environment.

At the same time, there's no value in using the cache while installing
bundled modules.

This change disables PIP caching when used in ensurepip.
(cherry picked from commit 4a3a682b12f93a03888e8b59f439bc5fe30d6055)

Co-authored-by: Krzysztof Konopko <kkonopko@users.noreply.github.com>
---
 Lib/ensurepip/__init__.py                        |  2 +-
 Lib/test/test_ensurepip.py                       | 16 ++++++++--------
 Misc/ACKS                                        |  1 +
 .../2020-06-15-12-22-53.bpo-40448.1dk8Bu.rst     |  2 ++
 4 files changed, 12 insertions(+), 9 deletions(-)
 create mode 100644 Misc/NEWS.d/next/Library/2020-06-15-12-22-53.bpo-40448.1dk8Bu.rst

diff --git a/Lib/ensurepip/__init__.py b/Lib/ensurepip/__init__.py
index 948f34092435a5b..7c5baf0b5f1a7c1 100644
--- a/Lib/ensurepip/__init__.py
+++ b/Lib/ensurepip/__init__.py
@@ -114,7 +114,7 @@ def _bootstrap(*, root=None, upgrade=False, user=False,
             additional_paths.append(os.path.join(tmpdir, wheel_name))
 
         # Construct the arguments to be passed to the pip command
-        args = ["install", "--no-index", "--find-links", tmpdir]
+        args = ["install", "--no-cache-dir", "--no-index", "--find-links", tmpdir]
         if root:
             args += ["--root", root]
         if upgrade:
diff --git a/Lib/test/test_ensurepip.py b/Lib/test/test_ensurepip.py
index 89966893092851c..4786d28f39a3d04 100644
--- a/Lib/test/test_ensurepip.py
+++ b/Lib/test/test_ensurepip.py
@@ -40,7 +40,7 @@ def test_basic_bootstrapping(self):
 
         self.run_pip.assert_called_once_with(
             [
-                "install", "--no-index", "--find-links",
+                "install", "--no-cache-dir", "--no-index", "--find-links",
                 unittest.mock.ANY, "setuptools", "pip",
             ],
             unittest.mock.ANY,
@@ -54,7 +54,7 @@ def test_bootstrapping_with_root(self):
 
         self.run_pip.assert_called_once_with(
             [
-                "install", "--no-index", "--find-links",
+                "install", "--no-cache-dir", "--no-index", "--find-links",
                 unittest.mock.ANY, "--root", "/foo/bar/",
                 "setuptools", "pip",
             ],
@@ -66,7 +66,7 @@ def test_bootstrapping_with_user(self):
 
         self.run_pip.assert_called_once_with(
             [
-                "install", "--no-index", "--find-links",
+                "install", "--no-cache-dir", "--no-index", "--find-links",
                 unittest.mock.ANY, "--user", "setuptools", "pip",
             ],
             unittest.mock.ANY,
@@ -77,7 +77,7 @@ def test_bootstrapping_with_upgrade(self):
 
         self.run_pip.assert_called_once_with(
             [
-                "install", "--no-index", "--find-links",
+                "install", "--no-cache-dir", "--no-index", "--find-links",
                 unittest.mock.ANY, "--upgrade", "setuptools", "pip",
             ],
             unittest.mock.ANY,
@@ -88,7 +88,7 @@ def test_bootstrapping_with_verbosity_1(self):
 
         self.run_pip.assert_called_once_with(
             [
-                "install", "--no-index", "--find-links",
+                "install", "--no-cache-dir", "--no-index", "--find-links",
                 unittest.mock.ANY, "-v", "setuptools", "pip",
             ],
             unittest.mock.ANY,
@@ -99,7 +99,7 @@ def test_bootstrapping_with_verbosity_2(self):
 
         self.run_pip.assert_called_once_with(
             [
-                "install", "--no-index", "--find-links",
+                "install", "--no-cache-dir", "--no-index", "--find-links",
                 unittest.mock.ANY, "-vv", "setuptools", "pip",
             ],
             unittest.mock.ANY,
@@ -110,7 +110,7 @@ def test_bootstrapping_with_verbosity_3(self):
 
         self.run_pip.assert_called_once_with(
             [
-                "install", "--no-index", "--find-links",
+                "install", "--no-cache-dir", "--no-index", "--find-links",
                 unittest.mock.ANY, "-vvv", "setuptools", "pip",
             ],
             unittest.mock.ANY,
@@ -260,7 +260,7 @@ def test_basic_bootstrapping(self):
 
         self.run_pip.assert_called_once_with(
             [
-                "install", "--no-index", "--find-links",
+                "install", "--no-cache-dir", "--no-index", "--find-links",
                 unittest.mock.ANY, "setuptools", "pip",
             ],
             unittest.mock.ANY,
diff --git a/Misc/ACKS b/Misc/ACKS
index a6da4f128982838..a893fdce0e9ac24 100644
--- a/Misc/ACKS
+++ b/Misc/ACKS
@@ -860,6 +860,7 @@ Vajrasky Kok
 Guido Kollerie
 Jacek Kołodziej
 Jacek Konieczny
+Krzysztof Konopko
 Arkady Koplyarov
 Peter A. Koren
 Марк Коренберг
diff --git a/Misc/NEWS.d/next/Library/2020-06-15-12-22-53.bpo-40448.1dk8Bu.rst b/Misc/NEWS.d/next/Library/2020-06-15-12-22-53.bpo-40448.1dk8Bu.rst
new file mode 100644
index 000000000000000..a755c5faa671c33
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2020-06-15-12-22-53.bpo-40448.1dk8Bu.rst
@@ -0,0 +1,2 @@
+:mod:`ensurepip` now disables the use of `pip` cache when installing the
+bundled versions of `pip` and `setuptools`.  Patch by Krzysztof Konopko.