[NTG-context] Restarting with different engine fails

Dear list, ConTeXt allows to select the engine in the preamble with a “magic comment”. The preamble is parsed and the engine restarted with new options. The following MWE fails in the latest beta % engine=luajittex \starttext Fail \stoptext with the error message texmf-context/scripts/context/lua/mtx-context.lua:427: attempt to call a nil value (global 'restart') If I uncomment the restart function and its helpers around line 110 it works. Please fix. Cheers, Henri