img2img not working with DDIM trailing or TCD

[wbruna]

This is on master-10c6501:

1. ./sd --model SD/cyberrealisticSemi_v30.safetensors -W 384 --seed 1 -p 'red shirt' --sampling-method ddim_trailing -o base.png to create the base image (just to be sure DDIM itself is working)
2. ./sd --model SD/cyberrealisticSemi_v30.safetensors -W 384 --seed 1 -p 'pink shirt' --mode img2img -i base.png --strength 0.1 --sampling-method euler -o i2i_euler_s1.png
3. ./sd --model SD/cyberrealisticSemi_v30.safetensors -W 384 --seed 1 -p 'pink shirt' --mode img2img -i base.png --strength 0.6 --sampling-method euler -o i2i_euler_s6.png
4. ./sd --model SD/cyberrealisticSemi_v30.safetensors -W 384 --seed 1 -p 'pink shirt' --mode img2img -i base.png --strength 0.1 --sampling-method tcd -o i2i_tcd_s1.png
5. ./sd --model SD/cyberrealisticSemi_v30.safetensors -W 384 --seed 1 -p 'pink shirt' --mode img2img -i base.png --strength 0.6 --sampling-method ddim_trailing -o i2i_ddim_s6.png

base	i2i_euler_s1	i2i_euler_s6	i2i_tcd_s1	i2i_ddim_s6

Both TCD and DDIM produce pretty much the same results for the same number of steps.

@yslai , any ideas?