bedtools intersect -v fails with self

[endrebak]

cat f1.bed
chr1    1   2   a   0    +
bedtools intersect -v -s -a f1.bed -b f1.bed
chr1    1   2   a   0    +

I expected the output to be empty. It works without the -s (same strand) flag.

[endrebak]

Derp.