_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

Reproduce the failure with the Python pickle and io.BytesIO snippet in the issue, then inspect pickle.Pickler's memo handling around a failed container dump. Done means a later dump does not reference memo entries absent from the output stream, with regression coverage for the demonstrated sequence.