pythongh-127060: Disable traceback colors in IDLE (python#128028)

Set TERM environment variable to "dumb" to disable traceback colors
in IDLE, since IDLE doesn't understand ANSI escape sequences.

Author: vstinner

Lib/idlelib/pyshell.py

@@ -424,7 +424,9 @@ def __init__(self, tkconsole):
     def spawn_subprocess(self):
         if self.subprocess_arglist is None:
             self.subprocess_arglist = self.build_subprocess_arglist()
-        self.rpcsubproc = subprocess.Popen(self.subprocess_arglist)
+        # gh-127060: Disable traceback colors
+        env = dict(os.environ, TERM='dumb')
+        self.rpcsubproc = subprocess.Popen(self.subprocess_arglist, env=env)
 
     def build_subprocess_arglist(self):
         assert (self.port!=0), (

Misc/NEWS.d/next/Library/2024-12-17-13-21-52.gh-issue-127060.mv2bX6.rst

@@ -0,0 +1,2 @@
+Set TERM environment variable to "dumb" to disable traceback colors in IDLE,
+since IDLE doesn't understand ANSI escape sequences. Patch by Victor Stinner.