Why is in the reaction of cyclic unsaturated aldehydes with hydrazine and hydrogen peroxide the aldehyde preserved? Question
  What is the product of this reaction?
  
  
  The answer given:
  


At first, I thought this was a typical Wolff-Kishner reduction, but then I saw the reagents didn't match up (no $\ce{OH-}$). 

How is this getting formed? Shouldn't the $\ce{CHO}$ group be reduced? What am I missing here?
The reaction of $\ce{H2O2}$ with hydrazine forms diazene, $\ce{HN=NH}$.  This reacts in a syn fashion to deliver both hydrogens to the same side of the alkene.