ComfyUI Base 2.9.0: SAGE_REF can finally do what it was documented to do

SAGE_REF is described as the way to pin SageAttention, but the clone used --depth 1 --branch "$SAGE_REF",
and --branch takes a branch or a tag and refuses a commit. MEASURED: git clone --depth 1 --branch <40-hex>
answers "Remote branch not found in upstream origin", so passing a commit failed at the clone for as
long as the knob has existed. A commit is fetched by object name now, and it also short-circuits the
ls-remote that resolves the cache key, which lists refs and would have resolved a commit to nothing.

The DEFAULT stays main, deliberately. The wheel cache is keyed on the resolved upstream commit precisely so
that tracking upstream costs nothing, and a version-keyed cache would be exactly the stale pin the comment
above that cache key refuses. So this does not pin SageAttention; it makes the pin available to anyone who
wants one, without making everyone else carry it.

Also: the RunPod fixture in suite/test_podctl.py carried a real-looking machineId and dataCenterId among its
obviously-fake fakevol001 and faketmpl02. Both are fake now, in all five places they appeared.

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Step one on a fresh machine:

python3 -m zipfile -e comfyui-base.zip . && bash comfyui-base/comfyui-base-script.sh