Gracefully handle CSV IO when file descriptor closed.

[Bug #10504][ruby-core:66240]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@59642 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

lib/csv.rb

@@ -1291,7 +1291,7 @@ class CSV
       begin
         yield csv
       ensure
-        csv.close
+        csv.closed? || csv.close
       end
     else
       csv

test/csv/test_interface.rb

@@ -137,6 +137,14 @@ class TestCSV::Interface < TestCSV
     end
   end
 
+  def test_open_handles_prematurely_closed_file_descriptor_gracefully
+    assert_nothing_raised(Exception) do
+      CSV.open(@path) do |csv|
+        csv.close
+      end
+    end
+  end
+
   ### Test Write Interface ###
 
   def test_generate