Plugins do not honor the correct extension when run as a part of a multiproject build

I have a plugin with a component.xml described here.

I think the component.xml is correct - it certainly looks the
same as the plexus examples.

My project that uses this plugin works entirely correctly, unless it
is a part of a multiproject build, in which case it uses the wrong
extension. I don't know why this would be the case unless I've missed
something?

In same directory:
W:\kms\dev\apps\kms>mvn install
[INFO] Scanning for projects...
[INFO] ----------------------------------------------------------------------------
[INFO] Building KMS Application Code
[INFO] task-segment: [install]
[INFO] ----------------------------------------------------------------------------
[INFO] [cargo2:uberwar]
[INFO] [install:install]
[INFO] Installing W:\1244 - Knowledge Management System
(KMS)\dev\apps\kms\target\kms-2.0-SNAPSHOT.war to C:\Documents and
Settings\nig
el.magnay\.m2\repository\com\cswgroup\kms\kms\2.0-SNAPSHOT\kms-2.0-SNAPSHOT.war
[INFO] ----------------------------------------------------------------------------
[INFO] BUILD SUCCESSFUL
[INFO] ----------------------------------------------------------------------------
[INFO] Total time: 1 minute 9 seconds
[INFO] Finished at: Thu Nov 24 11:46:53 GMT 2005
[INFO] Final Memory: 3M/6M
[INFO] ----------------------------------------------------------------------------

As a part of a multiproject:
....
[INFO] ----------------------------------------------------------------------------
[INFO] Building KMS Application Code
[INFO] task-segment: [install]
[INFO] ----------------------------------------------------------------------------
[INFO] [cargo2:uberwar]
[INFO] [install:install]
[INFO] Installing W:\1244 - Knowledge Management System
(KMS)\dev\apps\kms\target\kms-2.0-SNAPSHOT.war to C:\Documents and
Settings\nig
el.magnay\.m2\repository\com\cswgroup\kms\kms\2.0-SNAPSHOT\kms-2.0-SNAPSHOT.uberwar
....

Config of plugin:
<component-set>
<components>
<component>
<role>org.apache.maven.lifecycle.mapping.LifecycleMapping</role>
<role-hint>uberwar</role-hint>
<implementation>org.apache.maven.lifecycle.mapping.DefaultLifecycleMapping</implementation>
<configuration>
<phases>
<package>
org.codehaus.cargo.maven2:cargo-maven2-plugin:uberwar
</package>
<install>org.apache.maven.plugins:maven-install-plugin:install</install>
<deploy>org.apache.maven.plugins:maven-deploy-plugin:deploy</deploy>
</phases>
</configuration>
</component>

<component>
<role>org.apache.maven.artifact.handler.ArtifactHandler</role>
<role-hint>uberwar</role-hint>
<implementation>org.apache.maven.artifact.handler.DefaultArtifactHandler</implementation>
<configuration>
<type>uberwar</type>
<extension>war</extension>
<packaging>uberwar</packaging>
</configuration>
</component>
</components>
</component-set>