How to automate a job in Jenkins?

How to automate a job in Jenkins?

I am using Maven Release Plugin for automate the build & release
process.Its working fine but one problem I am facing.
I have created a job, which is checking trunk in every 15 mins, if any
changes found it starts the build & release process.And its working fine.
But , small problem is when the release:prepare is executing , it is
creating the tag and auto increment the trunk/pom.xml version (with
SNAPSHOT) to next release version-SNAPSHOT.
Suppose my current build version is 2.0-SNAPSHOT. After successfully build
it create the tag with only 2.0 (without SNAPSHOT). Also it auto
increments the pom.xml inside trunk to 2.1-SNAPSHOT.
The problem is , when my Jenkins (crontab) checking the trunk in every 15
mins ,it is found a new version inside the trunk (i.e. pom.xml ). And it
creates another build again. This process is happening again and
again.Where I know there is no code changes in trunk, only version has
incremented by release:prepare command.
Below I am giving the screen shot of Jenkins for reference.

Any help would be appreciated. Thanks in advance.