Update an existing merge request.

        :param project_id: ID of the project originating the merge request
        :param mergerequest_id: ID of the merge request to accept
        :param merge_commit_message: Custom merge commit message
        :return: dict of the modified merge request

def acceptmergerequest(self, project_id, mergerequest_id, merge_commit_message=None):
        """
        Update an existing merge request.

        :param project_id: ID of the project originating the merge request
        :param mergerequest_id: ID of the merge request to accept
        :param merge_commit_message: Custom merge commit message
        :return: dict of the modified merge request
        """

        data = {'merge_commit_message': merge_commit_message}

        request = requests.put(
            '{0}/{1}/merge_request/{2}/merge'.format(self.projects_url, project_id, mergerequest_id),
            data=data, headers=self.headers, verify=self.verify_ssl, auth=self.auth, timeout=self.timeout)

        if request.status_code == 200:
            return request.json()
        else:
            return False