comparison of Array with Array failed error

[shitpoet]

non-critical

sf fails with comparison of Array with Array failed error if name of some image contains double dash "--" f.ex. prev--disabled.png

i use this command for sf:
sf --layout packed --library chunkypng --selector 'i.icon-' --cssurl '../img' --output-image img/sprites.png --output-style css/_sprites.stl --pngcrush img/sprites