fixes shellwords usage for ruby 1.8.6 compat

lib/hub/commands.rb

@@ -724,8 +724,8 @@ help
     def expand_alias(cmd)
       if expanded = git_alias_for(cmd)
         if expanded.index('!') != 0
-          require 'shellwords' unless expanded.respond_to? :shellsplit
-          expanded.shellsplit
+          require 'shellwords' unless defined?(::Shellwords)
+          Shellwords.shellwords(expanded)
         end
       end
     end

lib/hub/context.rb

@@ -15,14 +15,16 @@ module Hub
       end
 
       def to_exec(args)
-        args = args.shellsplit if args.respond_to? :shellsplit
+        args = Shellwords.shellwords(args) if args.respond_to? :to_str
         Array(executable) + Array(args)
       end
     end
 
     # Caches output when shelling out to git
     GIT_CONFIG = ShellOutCache.new(ENV['GIT'] || 'git') do |cache, cmd|
-      result = %x{#{cache.to_exec(cmd).shelljoin}}.chomp
+      full_cmd = cache.to_exec(cmd)
+      cmd_string = full_cmd.respond_to?(:shelljoin) ? full_cmd.shelljoin : full_cmd.join(' ')
+      result = %x{#{cmd_string}}.chomp
       cache[cmd] = $?.success? && !result.empty? ? result : nil
     end