_pickle.UnpicklingError: Memo value not found at index 1

Bug report

Bug description:

When pickling a container object. The pickler class will store child-objects to its self.memo even if the container could not be fully pickled (and not written to the output).
This can cause references to memo objects that are not in the output stream.

import sys
import pickle
import io

buf = io.BytesIO()
pickler = pickle.Pickler(buf)
i_will_be_memorized = 'qqqqqqqqqqqq'
i_cant_be_pickled = sys

try:
    pickler.dump([i_will_be_memorized, i_cant_be_pickled])
except TypeError:
    # i_will_be_memorized is now in pickler memory despite the exception
    pass

# this dump will use the memo
pickler.dump(i_will_be_memorized)

data = buf.getbuffer().tobytes()

# so this will fail with:
#   _pickle.UnpicklingError: Memo value not found at index 1
pickle.loads(data)

CPython versions tested on:

3.12

Operating systems tested on:

Windows

Linked PRs

• gh-125762
• gh-130231
• gh-130232

使用 issue 中的 Python pickle 和 io.BytesIO 程式碼片段重現該失敗，然後檢查 pickle.Pickler 在容器 dump 失敗時對 memo 的處理。完成的標準是，後續的 dump 不會參照輸出串流中不存在的 memo 項目，並且針對所示序列具備回歸測試涵蓋。