with_retry().batch() returns another input's result when only some inputs recover on retry

Finding: An external report against langchain-core 1.6.9 installed from master (Python 3.11.15, tenacity 9.1.4) says RunnableLambda(...).with_retry(stop_after_attempt=2, wait_exponential_jitter=False) can return the wrong item in batch() and abatch() when one input recovers on retry and another keeps failing. The reporter says their example batch of a, b, c printed ['A','A','C'] instead of an exception in b's slot, and that with return_exceptions=False nothing was raised (https://github.com/langchain-ai/langchain/issues/41162). Reported mechanism (reporter's hypothesis, not maintainer-confirmed): after the last attempt, inputs absent from results_map are filled with result.pop(0). The reporter says that list is the whole last-attempt output, including successes already stored, so a failed input can take a neighbor's success (https://github.com/langchain-ai/langchain/issues/41162). A commenter (author association NONE, no run logs shown) says they reproduced the same outputs on a local checkout, including silent wrong output without return_exceptions, and agreed with the diagnosis. The commenter calls this independent confirmation, but it is an external, unlogged claim and not KFA reproduction (https://github.com/langchain-ai/langchain/issues/41162#issuecomment-6072729041). Fix status: the reporter proposes tracking each input's latest exception by original index. A contributor later says they implemented this in #41178 using a last_exception_for dict, that the PR was closed by a bot because of assignment rules, and that they ask to be assigned to the issue so they can reopen the PR; they report tests pass, which is a self-claim (https://github.com/langchain-ai/langchain/issues/41162#issuecomment-6082729435). No merged commit or released fix appears in the supplied sources, so this is a proposed fix only. Scope: in the reporter's example, the slot of the permanently failing input (b) is reported to hold another input's output. The sources do not state which other slots may be affected in other mixed-retry scenarios. Affected released versions are unknown. The supplied sources give no workaround; this is limited to the supplied thread content, which may omit middle comments. Limitations: all evidence is external report/comment content; KFA did not reproduce it; no maintainer confirmation of cause; fix not shown merged or shipped.