release:prepare performs source generation

[Kallin Nagelberg]

I've noticed that when i execute release:prepare on one my projects that
generates sources it performs the generation. I don't see why it would do
this, as it does it again during release:perform.
The plugin config in that artifact's POM looks like the following. Is there
a way to prevent release:prepare from executing it?

<plugin>
                <groupId>com.mycomp</groupId>
                <artifactId>generator_plugin</artifactId>
                <version>${project.version}</version>
                <executions>
                    <execution>
                        <goals>
                            <goal>gen</goal>
                        </goals>
                        <phase>generate-sources</phase>
                    </execution>
                </executions>
            </plugin>


Thanks,
Kal.