gh-101517: make bdb avoid looking up in linecache with lineno=None (GH-101787)

(cherry picked from commit 366b94905869d680b3f1d4801fb497e78811e511)

Co-authored-by: Irit Katriel <1055913+iritkatriel@users.noreply.github.com>

1 files changed, 4 insertions, 3 deletions

diff --git a/Lib/bdb.py b/Lib/bdb.py
index 81fbb85..7f9b095 100644
--- a/Lib/bdb.py
+++ b/Lib/bdb.py
@@ -570,9 +570,10 @@ class Bdb:
             rv = frame.f_locals['__return__']
             s += '->'
             s += reprlib.repr(rv)
-        line = linecache.getline(filename, lineno, frame.f_globals)
-        if line:
-            s += lprefix + line.strip()
+        if lineno is not None:
+            line = linecache.getline(filename, lineno, frame.f_globals)
+            if line:
+                s += lprefix + line.strip()
         return s
 
     # The following methods can be called by clients to use