The bar chart needs to be constructed with the entries of hist centred on the corresponding bins, but the bins array contains the bin boundaries:
In [x]: print(bins)
[ 0. 20. 40. 60. 80. 100.]
So construct an array containing the bin centres:
In [x]: bin_centres = (bins[:-1] + bins[1:])/2
In [x]: print(bin_centres)
[ 10. 30. 50. 70. 90.]
Then call pylab.bar specifying the width of each bin, and centering the bars on the values in bin_centres:
In [x]: pylab.bar(bin_centres, hist, width=20, align='center')