GH-106734: Disable tab completion in pdb's multiline mode (GH-106735)

Lib/pdb.py

@@ -514,6 +514,22 @@ class Pdb(bdb.Bdb, cmd.Cmd):
         if obj is not None:
             self.message(repr(obj))
 
+    @contextmanager
+    def _disable_tab_completion(self):
+        if self.use_rawinput and self.completekey == 'tab':
+            try:
+                import readline
+            except ImportError:
+                yield
+                return
+            try:
+                readline.parse_and_bind('tab: self-insert')
+                yield
+            finally:
+                readline.parse_and_bind('tab: complete')
+        else:
+            yield
+
     def default(self, line):
         if line[:1] == '!': line = line[1:].strip()
         locals = self.curframe_locals
@@ -521,6 +537,7 @@ class Pdb(bdb.Bdb, cmd.Cmd):
         try:
             if (code := codeop.compile_command(line + '\n', '<stdin>', 'single')) is None:
                 # Multi-line mode
+                with self._disable_tab_completion():
                     buffer = line
                     continue_prompt = "...   "
                     while (code := codeop.compile_command(buffer, '<stdin>', 'single')) is None:

Misc/NEWS.d/next/Library/2023-07-14-01-47-39.gh-issue-106734.eMYSoz.rst

@@ -0,0 +1 @@
+Disable tab completion in multiline mode of :mod:`pdb`