Velocity tools / Message Tool - ambiguous method invocation with latest SVN head (1.6)

I compiled the latest SVN head of Velocity today. Template memory consumption has gone down a lot. Great work!

However, I noticed that i18n string in my templates don't work anymore.

I have a properties file with:
toolbar.loggedin=Logged in as <b>

</b>

in the toolbox.xml:

<tool>
<key>msg</key>
<scope>request</scope>
<class>
org.apache.velocity.tools.struts.MessageTool
</class>
</tool>

In the template file I have a string:
$msg.toolbar.loggedin.insert("joe")

This works with Velocity 1.5 and Velocity tools 1.4 fine but with latest SVN head build the velocity.log shows:

Introspection Error : Ambiguous method invocation insert(java.lang.String) for class class org.apache.velocity.tools.struts.MessageTool$TextKey

and the message isn't rendered at all.

Any idea what's wrong?