Fix `Liquid Exception: comparison of Array with Array failed in page`

PROBLEM

When every page which declares tag has the same tags then running:

$ rake generate

the plugins breaks with the following exception:

## Generating Site with Jekyll
    write source/stylesheets/screen.css
Configuration file: ... /_config.yml
            Source: source
       Destination: public
      Generating...
  Liquid Exception: comparison of Array with Array failed in _layouts/page.html
jekyll 2.5.3 | Error:  comparison of Array with Array failed

CAUSE

When each tag occures the same number of times, calculated over all the posts, then in the logarithmic distribution expression:

# logarithmic distribution
weight = (Math.log(count) - Math.log(min))/(Math.log(max) - Math.log(min))

min is equal to max so weight assume the value NaN which make comparison with numbers fails.

SOLUTION

Use logarithmic distribution only if min is not equals to max otherwise use the value:

# value which makes the font-size calculated below equal to 100%
weight = (100 - size_min) / (size_max - size_min)

The value proposed for weight is the one which makes the font-size calculated few lines below equals to 100%:

size = size_min + ((size_max - size_min) * weight).to_f

in other words as none of each tag occures more then another one then all tags font-size must be the same: 100% is exactly the font-size of the text in the same block either <article> or <aside>.

robbyedwards/octopress-tag-cloud#1

robbyedwards / octopress-tag-cloud

Fix `Liquid Exception: comparison of Array with Array failed in page` #5