From 8662248774fae518b35f1ec5fdc437c0ae68b4bc Mon Sep 17 00:00:00 2001
From: Jon Dufresne <jon.dufresne@gmail.com>
Date: Sat, 21 Nov 2020 07:20:19 -0800
Subject: [PATCH] Always close stderr after subprocess completion in
 call_subprocess()

When running Python with warnings enabled, fixes warnings of the form:

    .../site-packages/pip/_internal/vcs/versioncontrol.py:773: ResourceWarning: unclosed file <_io.BufferedReader name=12>
      return call_subprocess(cmd, cwd,
---
 news/9156.bugfix.rst                    | 1 +
 src/pip/_internal/vcs/versioncontrol.py | 2 ++
 2 files changed, 3 insertions(+)
 create mode 100644 news/9156.bugfix.rst

diff --git a/news/9156.bugfix.rst b/news/9156.bugfix.rst
new file mode 100644
index 000000000..9b433fae2
--- /dev/null
+++ b/news/9156.bugfix.rst
@@ -0,0 +1 @@
+Fix ResourceWarning in VCS subprocesses
diff --git a/src/pip/_internal/vcs/versioncontrol.py b/src/pip/_internal/vcs/versioncontrol.py
index 219f79673..6724dcc69 100644
--- a/src/pip/_internal/vcs/versioncontrol.py
+++ b/src/pip/_internal/vcs/versioncontrol.py
@@ -150,6 +150,8 @@ def call_subprocess(
     finally:
         if proc.stdout:
             proc.stdout.close()
+        if proc.stderr:
+            proc.stderr.close()
 
     proc_had_error = (
         proc.returncode and proc.returncode not in extra_ok_returncodes