Fix that FakeFS method wouldn't call ::FakeFS.deactivate! when block raised an exception

lib/fakefs/base.rb

@@ -31,8 +31,8 @@ end
 def FakeFS
   return ::FakeFS unless block_given?
   ::FakeFS.activate!
-  result = yield
-  ::FakeFS.deactivate!
-  result
+  yield
+ensure
+::FakeFS.deactivate!
 end
 

test/safe_test.rb

@@ -26,4 +26,17 @@ class FakeFSSafeTest < Test::Unit::TestCase
 
     assert_equal result, "Yatta!"
   end
+  
+  def test_FakeFS_method_deactivates_FakeFS_when_block_raises_exception
+    begin
+      FakeFS do
+        raise 'boom!'
+      end
+    rescue
+    end
+    
+    assert_equal RealFile, File, "File is #{File} (should be #{RealFile})"
+    assert_equal RealFileUtils, FileUtils, "FileUtils is #{FileUtils} (should be #{RealFileUtils})"    
+    assert_equal RealDir, Dir, "Dir is #{Dir} (should be #{RealDir})"
+  end  
 end