From 3f96d54af2347db540541f5c5dd1f6fd24592e1a Mon Sep 17 00:00:00 2001
From: John Sirois <john.sirois@gmail.com>
Date: Mon, 30 Sep 2024 12:24:05 -0700
Subject: [PATCH] Add repl support for `PYTHON_COLORS`. (#2545)

This is new CPython env var knob in Python 3.13.
---
 pex/repl/custom.py | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/pex/repl/custom.py b/pex/repl/custom.py
index e5572d95c..35a429999 100644
--- a/pex/repl/custom.py
+++ b/pex/repl/custom.py
@@ -84,6 +84,11 @@ def _try_enable_readline(
 def _use_color():
     # type: () -> bool
 
+    # Used in Python 3.13+
+    python_colors = os.environ.get("PYTHON_COLORS")
+    if python_colors in ("0", "1"):
+        return python_colors == "1"
+
     # A common convention; see: https://no-color.org/
     if "NO_COLOR" in os.environ:
         return False
@@ -92,7 +97,7 @@ def _use_color():
     if "FORCE_COLOR" in os.environ:
         return True
 
-    return sys.stdout.isatty() and "dumb" != os.environ.get("TERM")
+    return sys.stderr.isatty() and "dumb" != os.environ.get("TERM")
 
 
 def repl_loop(