Fix 'ls -g' shows colored results. If Ruby is post 1.9.2 global_variables returns Array of symbol. So change them to string to compare BUILTIN_GLOBALS or PSEUDO_GLOBALS.

lib/pry/commands/ls/globals.rb

@@ -33,6 +33,7 @@ class Pry
 
       def format(globals)
         globals.sort_by(&:downcase).map do |name|
+          name = name.to_s
           if PSEUDO_GLOBALS.include?(name)
             color(:pseudo_global, name)
           elsif BUILTIN_GLOBALS.include?(name)