Check that 'new development version' is a SNAPSHOT version

While executing 'mvn release:prepare' one gets asked for the new development version like this:
What is the new development version for "foo"? (com.bar:foo) 1.12-SNAPSHOT:

Say I want the new development version to be 2.0-SNAPSHOT (and not like suggested 1.12-SNAPSHOT) but by accident I only enter 2.0. This will work just fine until I want to execute 'mvn release:prepare' again at some later point. Then I will get the error message that the current version is not a SNAPSHOT version.

It would be really nice if release:prepare could check if I have entered a valid SNAPSHOT version. If not release:prepare should fail or even nicer ask me to enter a proper SNAPSHOT version.