external package dependency conflicts pytorch development

[yangw-dev]

Overview

curious what we should do when the external dependency blocks the torch development

Issue

In aug 25, the vllm build in pytorch ci breaks,
it's not due to vllm itsself but flashinfer.

the pr causes the break:
pytorch/pytorch#160754

this is bc flashinfer have dependency on _get_pybind11_abi_build_flags(), but the pr
https://github.com/flashinfer-ai/flashinfer/blob/main/flashinfer/jit/cpp_ext.py#L19

seems like chicken and egg problem, create this issue to open to discuss
how to resolve those external dependency issues , while not blocking pytorch development. will create an issue for the team to discuss