busybox-1.19.3/shell/hush_test/hush-vars/var_preserved.tests

export a=b

# external program
a=c /bin/true
env | grep ^a=

# builtin
a=d true
env | grep ^a=

# exec with redirection only
# in bash, this leaks!
a=e exec 1>&1
env | grep ^a=

echo OK