Bokeh confusion matrix plot bug

gistfile1.py

#cf https://groups.google.com/a/continuum.io/forum/#!msg/bokeh/rvFcJV5_WQ8/Pf5hsF9mCAAJ

from collections import OrderedDict

import numpy as np
from bokeh.plotting import figure, show, output_file
from bokeh.models import HoverTool, ColumnDataSource


N = 20
arr2d = np.random.randint(0,10,size=(N,N))

predicted = []
actual = []
count = []
color = []
alpha = []
the_color = '#cc0000'
for col in range(N):
  for rowi in range(N):
    predicted.append(str(rowi))
    actual.append(str(col))
    count.append(arr2d[rowi,col])
    a = arr2d[rowi,col]/10.0
    alpha.append(a)
    color.append(the_color)
    
source = ColumnDataSource(
    data=dict(predicted=predicted, actual=actual, count=count, alphas=alpha, colors=color)
)

p = figure(title='Confusion Matrix',
     x_axis_location="above", tools="resize,hover,save",
     y_range=list(reversed(actual)), x_range=actual)
p.plot_width = 600
p.plot_height = p.plot_width

rectwidth = 10.9
p.rect('predicted', 'actual', rectwidth, rectwidth, source=source,
      color='colors', alpha='alphas',line_width=1, line_color='k')

p.axis.major_label_text_font_size = "12pt"
p.axis.major_label_standoff = 1
p.xaxis.major_label_orientation = np.pi/3

hover = p.select(dict(type=HoverTool))
hover.tooltips = OrderedDict([
    ('predicted', '@predicted'),
    ('actual', '@actual'),
    ('count', '@count'),
])

show(p)