pythongh-125378: Trigger a repeat for the full multi-line statement for empty line command (python#125717)

Author: gaogaotiantian

Lib/pdb.py

@@ -755,6 +755,7 @@ def default(self, line):
                             else:
                                 line = line.rstrip('\r\n')
                         buffer += '\n' + line
+                    self.lastcmd = buffer
             save_stdout = sys.stdout
             save_stdin = sys.stdin
             save_displayhook = sys.displayhook

Lib/test/test_pdb.py

@@ -2448,7 +2448,12 @@ def test_pdb_multiline_statement():
     ...     'def f(x):',
     ...     '  return x * 2',
     ...     '',
-    ...     'f(2)',
+    ...     'val = 2',
+    ...     'if val > 0:',
+    ...     '  val = f(val)',
+    ...     '',
+    ...     '',  # empty line should repeat the multi-line statement
+    ...     'val',
     ...     'c'
     ... ]):
     ...     test_function()
@@ -2457,8 +2462,13 @@ def test_pdb_multiline_statement():
     (Pdb) def f(x):
     ...     return x * 2
     ...
-    (Pdb) f(2)
-    4
+    (Pdb) val = 2
+    (Pdb) if val > 0:
+    ...     val = f(val)
+    ...
+    (Pdb)
+    (Pdb) val
+    8
     (Pdb) c
     """
 

Misc/NEWS.d/next/Library/2024-10-19-01-30-40.gh-issue-125378.WTosxX.rst

@@ -0,0 +1 @@
+Fixed the bug in :mod:`pdb` where after a multi-line command, an empty line repeats the first line of the multi-line command, instead of the full command.