Fix bug in jsonbytes.

src/allmydata/test/test_util.py

@@ -558,6 +558,12 @@ class JSONBytes(unittest.TestCase):
             expected
         )
 
+    def test_dumps_bytes_unicode_separators(self):
+        """Unicode separators don't prevent the result from being bytes."""
+        result = jsonbytes.dumps_bytes([1, 2], separators=(u',', u':'))
+        self.assertIsInstance(result, bytes)
+        self.assertEqual(result, b"[1,2]")
+
 
 class FakeGetVersion(object):
     """Emulate an object with a get_version."""

src/allmydata/util/jsonbytes.py

@@ -109,7 +109,7 @@ def dumps_bytes(obj, *args, **kwargs):
         human consumption.
     """
     result = dumps(obj, *args, **kwargs)
-    if PY3:
+    if PY3 or isinstance(result, str):
         result = result.encode("utf-8")
     return result