also set parallel_worker_number when working directly

lib/parallel.rb

@@ -277,6 +277,7 @@ def add_progress_bar!(job_factory, options)
     end
 
     def work_direct(job_factory, options, &block)
+      Thread.current[:parallel_worker_number] = 0
       results = []
       while set = job_factory.next
         item, index = set
@@ -285,6 +286,8 @@ def work_direct(job_factory, options, &block)
         end
       end
       results
+    ensure
+      Thread.current[:parallel_worker_number] = nil
     end
 
     def work_in_threads(job_factory, options, &block)

spec/cases/with_worker_number.rb

@@ -3,9 +3,8 @@
 method = ENV.fetch('METHOD')
 in_worker_type = "in_#{ENV.fetch('WORKER_TYPE')}".to_sym
 
-result = Parallel.public_send(method, 1..100, in_worker_type => 4) do
+Parallel.public_send(method, 1..100, in_worker_type => 4) do
   sleep 0.1 # so all workers get started
   print Thread.current[:parallel_worker_number]
-  nil
 end
 

spec/parallel_spec.rb

@@ -261,11 +261,17 @@ def cpus
         `METHOD=map WORKER_TYPE=#{type} ruby spec/cases/with_exception_in_start_before_finish.rb 2>&1`.should == '3 called'
       end
 
-      it "has access to thread local parallel_worker_number with #{type}" do
+      it "has access to thread local parallel_worker_number with 4 #{type}" do
         out = `METHOD=map WORKER_TYPE=#{type} ruby spec/cases/with_worker_number.rb`
         out.should =~ /\A[0123]+\z/
         %w(0 1 2 3).each { |number| out.should include number }
       end
+
+      it "has access to thread local parallel_worker_number with 0 #{type}" do
+        type_key = "in_#{type}".to_sym
+        Parallel.map([1,2,3,4,5,6,7,8,9], type_key => 0) { |x| Thread.current[:parallel_worker_number] }.uniq.should == [0]
+        Thread.current[:parallel_worker_number].should be_nil
+      end
     end
 
     it "can run with 0 threads" do