Reproducible kernel

fk@r500 /usr/src $time make -j2 buildkernel
--- buildkernel ---
--- reproducible_build_hint ---
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>>> To reproduce this build:
>>>  export REPRO_SEED=fk:r500.local:1453902579
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--- buildkernel ---
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>>> Kernel build for ELECTRO_BEER started on Wed Jan 27 13:49:39 UTC 2016
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