Rails 3.2.8, heroku: uninitialized constant Less :: Engine

Question

I see this error in the delayed work on the hero, and it makes no sense to me:

{uninitialized constant Less::Engine (in /app/app/assets/stylesheets/share_and_earn_recommendation_email.css.less) /app/vendor/bundle/ruby/1.9.1/gems/tilt-1.3.3/lib/tilt/css.rb:60:in `prepare' ... 

Why doesn’t it make sense? Since css.rb looks like this:

 def prepare if ::Less.const_defined? :Engine @engine = ::Less::Engine.new(data) # line 60 else ... 

This means that it is impossible to get to line 60 if Less::Engine is undefined. What am I missing?

EDIT

Even better demo from heroku console:

 irb(main):008:0> ::Less.const_defined? :Engine => true irb(main):009:0> ::Less::Engine NameError: uninitialized constant Less::Engine 

EDIT 2

This is becoming more interesting:

 irb(main):011:0> ::Less.const_defined? :Engine, false => false 

The difference is that the latter is not looking for ancestors. But there are no ancestors, so this should not matter:

 irb(main):012:0> ::Less.ancestors => [Less] 

Answer 1

If you just upgraded the rails version on the 3.2.x stack, you will find that in earlier versions, such as 3.2.2, less is present than in later versions, such as 3.2.9.

I did not fully investigate the problem, but I noticed that when I went to upgrade from 3.2.2 to 3.2.9, I had a few "fewer" problems.

Greetings