From 45a2d1ccd071a79a07b71c7187d50c25afa69432 Mon Sep 17 00:00:00 2001
From: Tian Gao <gaogaotiantian@hotmail.com>
Date: Tue, 20 Oct 2026 10:18:44 -0700
Subject: [PATCH 1/3] Ignore set_trace() when we are already in pdb

---
 Lib/bdb.py           |  7 +++++++
 Lib/test/test_pdb.py | 12 ++++++++++++
 2 files changed, 19 insertions(+)

diff --git a/Lib/bdb.py b/Lib/bdb.py
index f0601913ab3c8d..179111a6ae9901 100644
--- a/Lib/bdb.py
+++ b/Lib/bdb.py
@@ -600,6 +600,13 @@ def set_trace(self, frame=None):
 
         If frame is not specified, debugging starts from caller's frame.
         """
+
+        if self.enterframe is not None:
+            # If self.enterframe is not None, it means we are already in
+            # dispatched functions. Tracing is disabled when calling a
+            # trace function, so we just skip this set_trace() call.
+            return
+
         self.stop_trace()
         if frame is None:
             frame = sys._getframe().f_back
diff --git a/Lib/test/test_pdb.py b/Lib/test/test_pdb.py
index 8876b3f5ce37a3..697fb22e6ea8c2 100644
--- a/Lib/test/test_pdb.py
+++ b/Lib/test/test_pdb.py
@@ -4950,6 +4950,18 @@ def foo():
         stdout, _ = self._run_script(script, commands)
         self.assertIn("42", stdout)
 
+    def test_nested_set_trace(self):
+        # Calling breakpoint() in pdb prompt should just be ignored.
+        script = "breakpoint()"
+        commands = """
+            breakpoint()
+            p 40 + 2
+            c
+        """
+        stdout, stderr = self._run_script(script, commands)
+        self.assertIn('42', stdout)
+        self.assertEqual(stderr, '')
+
     def test_readline_not_imported(self):
         """GH-138860
         Directly or indirectly importing readline might deadlock a subprocess

From 1a43fa83c6d48a8384644b76e1ceace3c8c8c4f4 Mon Sep 17 00:00:00 2001
From: "blurb-it[bot]" <43283697+blurb-it[bot]@users.noreply.github.com>
Date: Tue, 20 Oct 2026 17:29:20 +0000
Subject: [PATCH 2/3] =?UTF-8?q?=F0=9F=93=9C=F0=9F=A4=96=20Added=20by=20blu?=
 =?UTF-8?q?rb=5Fit.?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 .../next/Library/2026-10-20-17-29-14.gh-issue-138641.FN6qM0.rst  | 1 +
 1 file changed, 1 insertion(+)
 create mode 100644 Misc/NEWS.d/next/Library/2026-10-20-17-29-14.gh-issue-138641.FN6qM0.rst

diff --git a/Misc/NEWS.d/next/Library/2026-10-20-17-29-14.gh-issue-138641.FN6qM0.rst b/Misc/NEWS.d/next/Library/2026-10-20-17-29-14.gh-issue-138641.FN6qM0.rst
new file mode 100644
index 00000000000000..af116c97c896d0
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2026-10-20-17-29-14.gh-issue-138641.FN6qM0.rst
@@ -0,0 +1 @@
+Ignore :func:`pdb.set_trace()` when running it directly from :mod:`pdb` prompts.

From 2ab55192369a243e235f7f18518c93ca1a0d5e6f Mon Sep 17 00:00:00 2001
From: Tian Gao <gaogaotiantian@hotmail.com>
Date: Tue, 20 Oct 2026 10:41:46 -0700
Subject: [PATCH 3/3] Fix news

---
 .../next/Library/2026-10-20-17-29-14.gh-issue-138641.FN6qM0.rst | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/Misc/NEWS.d/next/Library/2026-10-20-17-29-14.gh-issue-138641.FN6qM0.rst b/Misc/NEWS.d/next/Library/2026-10-20-17-29-14.gh-issue-138641.FN6qM0.rst
index af116c97c896d0..6d9ac174282839 100644
--- a/Misc/NEWS.d/next/Library/2026-10-20-17-29-14.gh-issue-138641.FN6qM0.rst
+++ b/Misc/NEWS.d/next/Library/2026-10-20-17-29-14.gh-issue-138641.FN6qM0.rst
@@ -1 +1 @@
-Ignore :func:`pdb.set_trace()` when running it directly from :mod:`pdb` prompts.
+Ignore :func:`pdb.set_trace` when called directly at the :mod:`pdb` prompt.