After Upgrading to v2.9.1, '@import "susy" is failing

[stonemirror]

I've been working through the book Sass and Compass for Designers and everything has been working fine with CodeKit. However, I upgraded to v2.9.1 today, and now a Compass compile which had been working for for some time is failing with the error message

LoadError on line ["55"] of /System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/lib/ruby/2.0.0/rubygems/core_ext/kernel_require.rb: cannot load such file -- susy

The file I'm compiling looks like this:

// ====================================================================
// Imports
// ====================================================================

@import "compass";
@import "susy";
@import "partials/variables";
@import "partials/mixins";
@import "partials/fonts";
@import "partials/normalize";
@import "partials/base";
@import "partials/layout";
@import "partials/modules";

Any ideas would be appreciated. If there's more information I can provide, please let me know.

[stonemirror]

Okay, after playing around some more, I'm concluding this is some sort of "pilot error". My bad.