Uploading Linear Assignment

I'd appreciate some help getting my patsy model to convert the test data into a matrix.  Patsy works fine on the training data--even when I pull out the design matrix builder--but it keeps throwing errors on the test data when it comes across categories it hasn't seen before.  I couldn't find a setting to get Patsy to ignore that, and adding in a try:/except: didn't work for obvious-in-retrospect reasons.