fix bdb: use slice copy in clear_all_file_breaks to avoid iterate-and-delete bug (gh-149015)

When multiple breakpoints share the same (filename, line), iterating the list
directly while calling deleteMe() (which removes from the same list) causes the
loop to skip alternate elements, leaving floor(N/2) orphan breakpoints.

The fix (for bp in blist: → for bp in blist[:]:) matches the existing defensive
pattern already used in clear_break() in the same file.

Added regression test test_clear_all_file_breaks_with_multiple_bps_same_line.

Author: AmSach

Lib/bdb.py

@@ -747,7 +747,7 @@ def clear_all_file_breaks(self, filename):
             return 'There are no breakpoints in %s' % filename
         for line in self.breaks[filename]:
             blist = Breakpoint.bplist[filename, line]
-            for bp in blist:
+            for bp in blist[:]:
                 bp.deleteMe()
         del self.breaks[filename]
         return None

Lib/test/test_bdb.py

@@ -1232,6 +1232,23 @@ def test_next_to_botframe(self):
 
 
 class TestRegressions(unittest.TestCase):
+    def test_clear_all_file_breaks_with_multiple_bps_same_line(self):
+        """Regression test: gh-149015.
+        clear_all_file_breaks must remove all breakpoints even when
+        multiple breakpoints share the same (file, line)."""
+        dbg = Bdb()
+        src = canonic(__file__)
+        dbg.set_break(src, 10)
+        dbg.set_break(src, 10)
+        dbg.set_break(src, 10)
+        self.assertEqual(len(Breakpoint.bplist[(src, 10)]), 3)
+        dbg.clear_all_file_breaks(src)
+        self.assertNotIn((src, 10), Breakpoint.bplist)
+        for bp in list(Breakpoint.bpbynumber):
+            if bp is not None:
+                bp.deleteMe()
+
+
     def test_format_stack_entry_no_lineno(self):
         # See gh-101517
         self.assertIn('Warning: lineno is None',