Support for mount points

- fixed incorrect argument in RenameObject
- added supports_drive_letter to tests where missing to succeed under
Linux
diff --git a/fake_filesystem_test.py b/fake_filesystem_test.py
index 65f0815..8e70503 100755
--- a/fake_filesystem_test.py
+++ b/fake_filesystem_test.py
@@ -3655,6 +3655,7 @@
     self.assertRaises(OSError, lambda: self.filesystem.AddMountPoint('/foo/'))
 
   def testThatDrivesAreAutoMounted(self):
+    self.filesystem.supports_drive_letter = True
     self.filesystem.CreateDirectory('d:/foo/bar')
     self.filesystem.CreateFile('d:/foo/baz')
     self.filesystem.CreateFile('z:/foo/baz')
@@ -3665,6 +3666,7 @@
 
   @unittest.skipIf(sys.version_info < (2, 7, 8), 'UNC path support since Python 2.7.8')
   def testThatUncPathsAreAutoMounted(self):
+    self.filesystem.supports_drive_letter = True
     self.filesystem.CreateDirectory('//foo/bar/baz')
     self.filesystem.CreateFile('//foo/bar/bip/bop')
     self.assertEqual(5, self.filesystem.GetObject('//foo/bar').st_dev)
diff --git a/pyfakefs/fake_filesystem.py b/pyfakefs/fake_filesystem.py
index 7d9dc72..5b4ed44 100644
--- a/pyfakefs/fake_filesystem.py
+++ b/pyfakefs/fake_filesystem.py
@@ -1256,7 +1256,7 @@
                       new_file)
       else:
         try:
-          self.RemoveObject(new_obj)
+          self.RemoveObject(new_file)
         except IOError as e:
           raise OSError(e.errno, e.strerror, e.filename)