Compilation fails on app that uses in-place plugin + references to interface defined in plugin + settings.groovy w/ Maven repository authentication settings

Background:

• One application, called TestApp and one plugin, called TestPlugin
• TestApp includes TestPlugin as an in-place plugin in its BuildConfig.groovy file
• TestApp has a Java interface (PluginInterface.java) with a method whose arguments include an interface defined TestPlugin (PluginInterface.java)
• The current user has a settings.groovy file in his USER_HOME/.grails folder
• The settings.groovy file includes grails.project.ivy.authentication or grails.project.dependency.distribution

"grails compile" of TestApp fails when javac fails with a "cannot find symbol" error.

Output of failed compilation:
F:\Docs\SVN\branches\Nick's Test Apps\InLinePlugInTest\TestApp>grails compile
Welcome to Grails 1.3.6 - http://grails.org/
Licensed under Apache Standard License 2.0
Grails home is set to: C:\Grails\grails-1.3.6

Base Directory: F:\Docs\SVN\branches\Nick's Test Apps\InLinePlugInTest\TestApp
Resolving dependencies...
Dependencies resolved in 1286ms.
Running script C:\Grails\grails-1.3.6\scripts\Compile.groovy
Environment set to development
[groovyc] Compiling 8 source files to F:\Docs\SVN\branches\Nick's Test Apps\InLinePlugInTest\TestApp\target\classes
[groovyc] org.codehaus.groovy.control.MultipleCompilationErrorsException: startup failed:
[groovyc] Compile error during compilation with javac.
[groovyc] F:\Docs\SVN\branches\Nick's Test Apps\InLinePlugInTest\TestApp\src\java\com\testco\AppInterface.java:5: cannot find symbol
[groovyc] symbol : class PluginInterface
[groovyc] location: interface com.testco.AppInterface
[groovyc] public void testMethod(PluginInterface pluginInterface);
[groovyc] ^
[groovyc] 1 error
[groovyc]
[groovyc]
[groovyc] 1 error
Compilation error: Compilation Failed

Sample settings.groovy that will cause compilation to fail:
grails.project.ivy.authentication = {}

If settings.groovy does not define grails.project.ivy.authentication or grails.project.dependency.distribution at all, compiling succeeds. Defining them to be anything at all (even empty closures) will cause compilation to fail. Their mere presence seems to cause compilations errors.

This makes using an in-house Maven repo and in-place plugins at the same time impossible.