Adding base level when interacting categorical variables

General Usage
,
1

High level problem:

reg from FixedEffectModels seem to ignore contrasts for a categorical variable if I interact this variable with another one.

MWE

df = DataFrame(y = rand(100), x1 = categorical(rand(1:3, 100)), x2 = categorical(rand(1:3, 100)))
# Regression of y ~ x1 using x1 = 2 as base
reg(df, @formula(y ~ x1); contrasts = Dict(:x1 => DummyCoding(base = 2)))
# Regression of y ~ x1&x2 using x1 = 2 as base 
reg(df, @formula(y ~ x1&x2); contrasts = Dict(:x1 => DummyCoding(base = 2)))

The first case works fine but the latter just takes the highest value of each regressor as base. It is not hard to re-convert but is there not a way of setting the base you want in the latter case?