Fixed crash when loading non-font bytes

Tests/test_imagefont.py

@@ -420,6 +420,10 @@ def test_load_path_not_found(self):
         self.assertRaises(IOError, ImageFont.load_path, filename)
         self.assertRaises(IOError, ImageFont.truetype, filename)
 
+    def test_load_non_font_bytes(self):
+        with open("Tests/images/hopper.jpg", "rb") as f:
+            self.assertRaises(IOError, ImageFont.truetype, f)
+
     def test_default_font(self):
         # Arrange
         txt = 'This is a "better than nothing" default font.'

src/PIL/ImageFont.py

@@ -545,6 +545,8 @@ def freetype(font):
     try:
         return freetype(font)
     except IOError:
+        if not isPath(font):
+            raise
         ttf_filename = os.path.basename(font)
 
         dirs = []

src/_imagingft.c

@@ -315,6 +315,7 @@ getfont(PyObject* self_, PyObject* args, PyObject* kw)
     if (error) {
         if (self->font_bytes) {
             PyMem_Free(self->font_bytes);
+            self->font_bytes = NULL;
         }
         Py_DECREF(self);
         return geterror(error);