Fixes _calc_cond_batch_multigpu so that:
1. conds_per_device uses real division before math.ceil. The previous
expression math.ceil(total_conds // len(devices)) applied integer
floor division first, making ceil a no-op. For 3 conds across 2
devices this produced conds_per_device=1 instead of 2.
2. The scheduling loop skips devices that have already reached
capacity instead of appending empty batch groups. Without this
guard, the loop could repeatedly emit zero-length groups for a
full device, leaving sampling stuck at 0/N until timeout.
Reproduces with an Omnigen2 image workflow that produces three
condition entries scheduled across two CUDA devices. With the fix
the scheduler assigns conds_per_device=2 and splits the batches as
2 + 1 across the two devices, allowing sampling to complete.
Original fix authored and validated by @pollockjj in
pollockjj/ComfyUI#64.
Co-authored-by: John Pollock <pollockjj@gmail.com>
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