set np.random's seed to a fixed value for random_seeds_from_mask doctests
set np.random's seed to a fixed value for random_seeds_from_mask doctests

StongeEtienne/dipy,oesteban/dipy,rfdougherty/dipy,demianw/dipy,jyeatman/dipy,oesteban/dipy,demianw/dipy,villalonreina/dipy,FrancoisRheaultUS/dipy,nilgoyyou/dipy,matthieudumont/dipy,FrancoisRheaultUS/dipy,sinkpoint/dipy,rfdougherty/dipy,villalonreina/dipy,matthieudumont/dipy,sinkpoint/dipy,StongeEtienne/dipy,jyeatman/dipy,JohnGriffiths/dipy,nilgoyyou/dipy,JohnGriffiths/dipy