release:prepare does not change the version of parent snapshot

In a project pom.xml, when the parent version is a snapshot : for example :

<parent>
<groupId>groupId</groupId>
<artifactId>artifcatId</artifactId>
<version>0.1-SNAPSHOT</version>
</parent>

Running "mvn release:prepare" prompt for

'groupId:artifactId set to release? (yes/no) yes: :
What is the next development version? (0.2-SNAPSHOT) 0.2-SNAPSHOT: :

But then it's still 0.1-SNAPSHOT in the release and in the new developpement version.
I expected the release version to be :
<parent>
<groupId>groupId</groupId>
<artifactId>artifcatId</artifactId>
<version>0.1</version>
</parent>
and the new developpement version :
<parent>
<groupId>groupId</groupId>
<artifactId>artifcatId</artifactId>
<version>0.2-SNAPSHOT</version>
</parent>

I attached an exemple.
Thanks for any feedback on this.

JP