externals options not applied to child compilations

[jorrit]

I have a webpack configuration with some externals set. These work fine in the base compilation. However, the modules that should be excluded are still present in the child compilations that ttag-webpack-plugin creates.
I have tried to find out how to solve this, but I haven't been able to find the cause. The childCompilation.options object contains the externals that I set, but there seems to be no effect.
It is not a showstopper for me, but it would be great to me if someone finds and fixes this problem. Thanks!