bpo-29566: binhex.binhex now consitently writes MacOS 9 line endings. (GH-23059)



[bpo-29566]() notes that binhex.binhex uses inconsistent line endings (both Unix and MacOS9 line endings are used). This PR changes this to use the MacOS9 line endings everywhere.
diff --git a/Lib/test/test_binhex.py b/Lib/test/test_binhex.py
index 5e59f57..efc1654 100644
--- a/Lib/test/test_binhex.py
+++ b/Lib/test/test_binhex.py
@@ -52,6 +52,18 @@ def test_binhex_error_on_long_filename(self):
 
         self.assertRaises(binhex.Error, binhex.binhex, self.fname3, self.fname2)
 
+    def test_binhex_line_endings(self):
+        # bpo-29566: Ensure the line endings are those for macOS 9
+        with open(self.fname1, 'wb') as f:
+            f.write(self.DATA)
+
+        binhex.binhex(self.fname1, self.fname2)
+
+        with open(self.fname2, 'rb') as fp:
+            contents = fp.read()
+
+        self.assertNotIn(b'\n', contents)
+
 def test_main():
     support.run_unittest(BinHexTestCase)