env/env.go
func (e *EnvVar) Set(key, value string) {
	keyVal := key + "=" + value
	for i, v := range *e {
		env := strings.SplitN(v, "=", 2)
		if len(env) < 2 {
			continue
		}
		if env[0] == key {
			(*e)[i] = keyVal
			return
		}
	}
	*e = append(*e, keyVal)
}
func (e *EnvVar) Set(key, value string) {
	keyVal := key + "=" + value
	for i, v := range *e {
		env := strings.SplitN(v, "=", 2)
		if len(env) < 2 {
			continue
		}
		if env[0] == key {
			(*e)[i] = keyVal
			return
		}
	}
	*e = append(*e, keyVal)
}
// Set sets the environment key to value.