在使用jenkins Email-ext plugin发送邮件时，项目中使用了SVN去同步，发现每次有同步，都会发送邮件，现只想SVN只更新，不发送邮件通知，这就要在Pre-send中做修改
看看官网说明：
Pre-send Script The pre-send script is a feature which allows you to write a script that can modify the MimeMessage object prior to sending. This would allow adding custom headers, modifying the body, etc. Predefined variables include: msg - the MimeMessage object which can be modified logger - a PrintStream and will write to the job's log. build - the build this message belongs to cancel - a boolean, which when set to true will cancel the sending of the email
只官网中可以看到cancel可以满足我们的需求，只要设置cancel为true就行，怎么设置呢？
下面这样写吗？
Jenkins > Manage > script if (build.changeSet.emptySet) cancel=true;
好像也不对，在多次尝试后，发出其实只需要这样写就可以
如下图：
