Defensive 1.9.3 support

Rakefile

@@ -2,7 +2,15 @@
 
 require_relative 'lib/concurrent/version'
 require_relative 'lib/concurrent/utility/engine'
-require_relative 'lib/concurrent/utility/193'
+
+if Concurrent.ruby_version :<, 2, 0, 0
+  # @!visibility private
+  module Kernel
+    def __dir__
+      File.dirname __FILE__
+    end
+  end
+end
 
 core_gemspec = Gem::Specification.load File.join(__dir__, 'concurrent-ruby.gemspec')
 ext_gemspec  = Gem::Specification.load File.join(__dir__, 'concurrent-ruby-ext.gemspec')

lib/concurrent.rb

@@ -1,5 +1,3 @@
-require 'concurrent/utility/193'
-
 require 'concurrent/version'
 require 'concurrent/constants'
 require 'concurrent/errors'

lib/concurrent/utility/native_extension_loader.rb

@@ -42,6 +42,14 @@ def load_native_extensions
 
       private
 
+      def load_error_path(error)
+        if error.respond_to? :path
+          error.path
+        else
+          error.message.split(' -- ').last
+        end
+      end
+
       def set_c_extensions_loaded
         @c_extensions_loaded = true
       end
@@ -54,7 +62,7 @@ def try_load_c_extension(path)
         require path
         set_c_extensions_loaded
       rescue LoadError => e
-        if e.path == path
+        if load_error_path(e) == path
           # move on with pure-Ruby implementations
           # TODO (pitr-ch 12-Jul-2018): warning on verbose?
         else