JRuby: occasionally builds fail

[anicholson]

Like this:

Failures:

  1) Truck behaves like an active object
     Failure/Error: Unable to find matching line from backtrace
     NoMethodError:
       undefined method `mine_state' for #<Mine::Machinery:0x5b73a116 run>
     Shared Example Group: "an active object" called from ./spec/entities/truck_spec.rb:5
     # ./lib/mining_depot/entities/mine.rb:88:in `machine'
     # ./lib/mining_depot/entities/mine.rb:87:in `machine'

Deprecation Warnings:

and this:

Failures:

  1) Mine#status return value 
     Failure/Error: Unable to find matching line from backtrace
     NoMethodError:
       undefined method `speed' for #<Mine:0x4a9aa2a7>
     # ./lib/mining_depot/entities/mine.rb:98:in `machine'
     # ./lib/mining_depot/entities/mine.rb:87:in `machine'