Fix all references to the old "_server_version" attribute.

peewee.py

@@ -3702,7 +3702,7 @@ def conflict_update(self, on_conflict, query):
             # Here we need to determine which function to use, which varies
             # depending on the MySQL server version. MySQL and MariaDB prior to
             # 10.3.3 use "VALUES", while MariaDB 10.3.3+ use "VALUE".
-            version = self._server_version or (0,)
+            version = self.server_version or (0,)
             if version[0] == 10 and version >= (10, 3, 3):
                 VALUE_FN = fn.VALUE
             else:

playhouse/mysql_ext.py

@@ -11,14 +11,7 @@ class MySQLConnectorDatabase(MySQLDatabase):
     def _connect(self):
         if mysql_connector is None:
             raise ImproperlyConfigured('MySQL connector not installed!')
-        conn = mysql_connector.connect(db=self.database, **self.connect_params)
-        if self._server_version is None:
-            # MySQL-Connector supports getting the version as a tuple, but this
-            # method does not return the proper MariaDB version on systems like
-            # Ubuntu, which express the version as 5.5.5-10.0.37-MariaDB-...
-            version_raw = conn.get_server_info()
-            self._server_version = self._extract_server_version(version_raw)
-        return conn
+        return mysql_connector.connect(db=self.database, **self.connect_params)
 
     def cursor(self, commit=None):
         if self.is_closed():

tests/base.py

@@ -89,7 +89,7 @@ def new_connection():
 IS_MYSQL_ADVANCED_FEATURES = False
 if IS_MYSQL:
     db.connect()
-    server_info = db._server_version
+    server_info = db.server_version
     if server_info[0] == 8 or server_info[:2] >= (10, 2):
         IS_MYSQL_ADVANCED_FEATURES = True
     elif server_info[0] == 0:

tests/sql.py

@@ -1465,7 +1465,7 @@ class TestOnConflictMySQL(BaseTestCase):
 
     def setUp(self):
         super(TestOnConflictMySQL, self).setUp()
-        self.database._server_version = None
+        self.database.server_version = None
 
     def test_replace(self):
         query = Person.insert(name='huey').on_conflict('replace')
@@ -1504,13 +1504,13 @@ def test_update_use_value_mariadb(self):
         query = (Person
                  .insert(name='huey', dob=dob)
                  .on_conflict(preserve=(Person.dob,)))
-        self.database._server_version = (10, 3, 3)
+        self.database.server_version = (10, 3, 3)
         self.assertSQL(query, (
             'INSERT INTO "person" ("dob", "name") VALUES (?, ?) '
             'ON DUPLICATE KEY '
             'UPDATE "dob" = VALUE("dob")'), [dob, 'huey'])
 
-        self.database._server_version = (10, 3, 2)
+        self.database.server_version = (10, 3, 2)
         self.assertSQL(query, (
             'INSERT INTO "person" ("dob", "name") VALUES (?, ?) '
             'ON DUPLICATE KEY '