Default wire version range is 0-6, not 2-6.

Leave the default minWireVersion as 0, not 2. I had been wrong about
MongoDB 3.6's wire version range, I thought it would be 2-6, but it's
0-6. MockupDB now has the same wire version range by default as MongoDB
3.6.

CHANGELOG.rst

@@ -3,6 +3,13 @@
 Changelog
 =========
 
+Next Release
+------------
+
+Set minWireVersion to 0, not to 2. I had been wrong about MongoDB 3.6's wire
+version range: it's actually 0 to 6. MockupDB now reports the same wire version
+range as MongoDB 3.6 by default.
+
 1.2.0 (2017-09-22)
 ------------------
 

mockupdb/__init__.py

@@ -1099,13 +1099,13 @@ class MockupDB(object):
         ismaster requests, or pass a dict or `OpReply`.
       - `ssl`: pass ``True`` to require SSL.
       - `min_wire_version`: the minWireVersion to include in ismaster responses
-        if `auto_ismaster` is True, default 2.
+        if `auto_ismaster` is True, default 0.
       - `max_wire_version`: the maxWireVersion to include in ismaster responses
         if `auto_ismaster` is True, default 6.
     """
     def __init__(self, port=None, verbose=False,
                  request_timeout=10, auto_ismaster=None,
-                 ssl=False, min_wire_version=2, max_wire_version=6):
+                 ssl=False, min_wire_version=0, max_wire_version=6):
         self._address = ('localhost', port)
         self._verbose = verbose
         self._label = None

tests/test_mockupdb.py

@@ -260,7 +260,7 @@ def test_default_wire_version(self):
         server.run()
         self.addCleanup(server.stop)
         ismaster = MongoClient(server.uri).admin.command('isMaster')
-        self.assertEqual(ismaster['minWireVersion'], 2)
+        self.assertEqual(ismaster['minWireVersion'], 0)
         self.assertEqual(ismaster['maxWireVersion'], 6)
 
     def test_wire_version(self):