raise error if ruby 1.9.3 is detected.

.travis.yml

@@ -2,7 +2,6 @@ language: ruby
 services:
   - redis-server
 rvm:
-  - 1.9.3
   - jruby-19mode
   - rbx-2
   - 2.0.0

lib/sidekiq.rb

@@ -1,5 +1,7 @@
 # encoding: utf-8
 require 'sidekiq/version'
+fail "Sidekiq #{Sidekiq::VERSION} does not support Ruby 1.9." if RUBY_PLATFORM != 'java' && RUBY_VERSION < '2.0.0'
+
 require 'sidekiq/logging'
 require 'sidekiq/client'
 require 'sidekiq/worker'
@@ -23,7 +25,7 @@ module Sidekiq
       :startup => [],
       :quiet => [],
       :shutdown => [],
-    },
+    }
   }
 
   def self.❨╯°□°❩╯︵┻━┻
@@ -66,7 +68,7 @@ module Sidekiq
   end
 
   def self.redis(&block)
-    raise ArgumentError, "requires a block" if !block
+    raise ArgumentError, "requires a block" unless block
     redis_pool.with(&block)
   end
 
@@ -143,8 +145,8 @@ module Sidekiq
   #     end
   #   end
   def self.on(event, &block)
-    raise ArgumentError, "Symbols only please: #{event}" if !event.is_a?(Symbol)
-    raise ArgumentError, "Invalid event name: #{event}" if !options[:lifecycle_events].keys.include?(event)
+    raise ArgumentError, "Symbols only please: #{event}" unless event.is_a?(Symbol)
+    raise ArgumentError, "Invalid event name: #{event}" unless options[:lifecycle_events].keys.include?(event)
     options[:lifecycle_events][event] << block
   end
 end

sidekiq.gemspec

@@ -13,7 +13,6 @@ Gem::Specification.new do |gem|
   gem.test_files    = `git ls-files -- test/*`.split("\n")
   gem.name          = "sidekiq"
   gem.require_paths = ["lib"]
-  gem.required_ruby_version = '>= 2.0.0'
   gem.version       = Sidekiq::VERSION
   gem.add_dependency                  'redis', '>= 3.0.6'
   gem.add_dependency                  'redis-namespace', '>= 1.3.1'