busybox/shell/ash_test/ash-vars/var_in_pipes.tests

b=1 env | grep ^b=
true | b=2 env | grep ^b=
a=1 true | b=3 env | grep ^b=

(b=4 env) | grep ^b=
(true | b=5 env) | grep ^b=
(a=1 true | b=6 env) | grep ^b=