prow/github/client.go
func (c *Client) ClearMilestone(org, repo string, num int) error {
	c.log("ClearMilestone", org, repo, num)

	issue := &struct {
		// Clearing the milestone requires providing a null value, and
		// interface{} will serialize to null.
		Milestone interface{} `json:"milestone"`
	}{}
	_, err := c.request(&request{
		method:      http.MethodPatch,
		path:        fmt.Sprintf("/repos/%v/%v/issues/%d", org, repo, num),
		requestBody: &issue,
		exitCodes:   []int{200},
	}, nil)
	return err
}
func (c *Client) ClearMilestone(org, repo string, num int) error {
	c.log("ClearMilestone", org, repo, num)

	issue := &struct {
		// Clearing the milestone requires providing a null value, and
		// interface{} will serialize to null.
		Milestone interface{} `json:"milestone"`
	}{}
	_, err := c.request(&request{
		method:      http.MethodPatch,
		path:        fmt.Sprintf("/repos/%v/%v/issues/%d", org, repo, num),
		requestBody: &issue,
		exitCodes:   []int{200},
	}, nil)
	return err
}
// ClearMilestone clears the milestone from the specified issue
//
// See https://developer.github.com/v3/issues/#edit-an-issue