prow/cmd/build/controller.go
func defaultEnv(c *coreapi.Container, rawEnv map[string]string) {
	keys := sets.String{}
	for _, arg := range c.Env {
		keys.Insert(arg.Name)
	}
	for _, k := range sets.StringKeySet(rawEnv).List() { // deterministic ordering
		if keys.Has(k) {
			continue
		}
		c.Env = append(c.Env, coreapi.EnvVar{Name: k, Value: rawEnv[k]})
	}
}
func defaultEnv(c *coreapi.Container, rawEnv map[string]string) {
	keys := sets.String{}
	for _, arg := range c.Env {
		keys.Insert(arg.Name)
	}
	for _, k := range sets.StringKeySet(rawEnv).List() { // deterministic ordering
		if keys.Has(k) {
			continue
		}
		c.Env = append(c.Env, coreapi.EnvVar{Name: k, Value: rawEnv[k]})
	}
}
// defaultEnv adds the map of environment variables to the container, except keys already defined.