split up all the build rake tasks for build to work

Rakefile

@@ -281,7 +281,13 @@ if (python?)
   task :test => [ :test_py ]
 end
 
-task :build => [:all, :firefox, :remote, :selenium, :tests]
+task :build do
+  Rake::Task[:all].execute
+  Rake::Task[:firefox].execute
+  Rake::Task[:remote].execute
+  Rake::Task[:selenium].execute
+  Rake::Task[:tests].execute
+end
 
 desc 'Clean build artifacts.'
 task :clean do