.PHONY: download
# atomically create file by command
-cmdsave = @echo $1 $2 \>$@; $1 $2 | sponge $@
+cmdsave = @echo $1 $2 \>$@; mispipe '$1 $2' 'ifne sponge $@'
# download git checkout
gitsave = @if cd $@ 2>/dev/null; \
then echo git pull $@; git pull -q --ff-only || true; \