prow/config/config.go
func (c *Config) mergeJobConfig(jc JobConfig) error {
	// Merge everything
	// *** Presets ***
	c.Presets = append(c.Presets, jc.Presets...)

	// validate no duplicated preset key-value pairs
	validLabels := map[string]bool{}
	for _, preset := range c.Presets {
		for label, val := range preset.Labels {
			pair := label + ":" + val
			if _, ok := validLabels[pair]; ok {
				return fmt.Errorf("duplicated preset 'label:value' pair : %s", pair)
			}
			validLabels[pair] = true
		}
	}

	// *** Periodics ***
	c.Periodics = append(c.Periodics, jc.Periodics...)

	// *** Presubmits ***
	if c.Presubmits == nil {
		c.Presubmits = make(map[string][]Presubmit)
	}
	for repo, jobs := range jc.Presubmits {
		c.Presubmits[repo] = append(c.Presubmits[repo], jobs...)
	}

	// *** Postsubmits ***
	if c.Postsubmits == nil {
		c.Postsubmits = make(map[string][]Postsubmit)
	}
	for repo, jobs := range jc.Postsubmits {
		c.Postsubmits[repo] = append(c.Postsubmits[repo], jobs...)
	}

	return nil
}
func (c *Config) mergeJobConfig(jc JobConfig) error {
	// Merge everything
	// *** Presets ***
	c.Presets = append(c.Presets, jc.Presets...)

	// validate no duplicated preset key-value pairs
	validLabels := map[string]bool{}
	for _, preset := range c.Presets {
		for label, val := range preset.Labels {
			pair := label + ":" + val
			if _, ok := validLabels[pair]; ok {
				return fmt.Errorf("duplicated preset 'label:value' pair : %s", pair)
			}
			validLabels[pair] = true
		}
	}

	// *** Periodics ***
	c.Periodics = append(c.Periodics, jc.Periodics...)

	// *** Presubmits ***
	if c.Presubmits == nil {
		c.Presubmits = make(map[string][]Presubmit)
	}
	for repo, jobs := range jc.Presubmits {
		c.Presubmits[repo] = append(c.Presubmits[repo], jobs...)
	}

	// *** Postsubmits ***
	if c.Postsubmits == nil {
		c.Postsubmits = make(map[string][]Postsubmit)
	}
	for repo, jobs := range jc.Postsubmits {
		c.Postsubmits[repo] = append(c.Postsubmits[repo], jobs...)
	}

	return nil
}
// mergeConfig merges two JobConfig together
// It will try to merge:
//	- Presubmits
//	- Postsubmits
// 	- Periodics
//	- PodPresets