PYTHON-1706 Fix issues found by coverity pt. 1 (mongodb#377)

Author: Marek Skalický

pymongo/database.py

@@ -1031,7 +1031,7 @@ def _create_or_update_user(
 
  opts["roles"] = [self._default_role(read_only)]
 
- elif read_only:
+ if read_only:
  warnings.warn("The read_only option is deprecated in MongoDB "
  ">= 2.6, use 'roles' instead", DeprecationWarning)
 

test/test_cursor.py

@@ -357,7 +357,7 @@ def test_explain_with_read_concern(self):
  self.assertTrue(coll.find().explain())
  started = listener.results['started']
  self.assertEqual(len(started), 1)
- self.assertNotIn("readConern", started[0].command)
+ self.assertNotIn("readConcern", started[0].command)
 
  def test_hint(self):
  db = self.db