[1.6.x] Fixed #22321 -- Wrapped exceptions in _set_autocommit.

Refs #21202.

Backport of 3becac84 from master

django/db/backends/mysql/base.py

@@ -457,7 +457,8 @@ class DatabaseWrapper(BaseDatabaseWrapper):
             pass
 
     def _set_autocommit(self, autocommit):
-        self.connection.autocommit(autocommit)
+        with self.wrap_database_errors:
+            self.connection.autocommit(autocommit)
 
     def disable_constraint_checking(self):
         """

django/db/backends/oracle/base.py

@@ -625,7 +625,8 @@ class DatabaseWrapper(BaseDatabaseWrapper):
         pass
 
     def _set_autocommit(self, autocommit):
-        self.connection.autocommit = autocommit
+        with self.wrap_database_errors:
+            self.connection.autocommit = autocommit
 
     def check_constraints(self, table_names=None):
         """

django/db/backends/postgresql_psycopg2/base.py

@@ -169,14 +169,15 @@ class DatabaseWrapper(BaseDatabaseWrapper):
             self.connection.set_isolation_level(isolation_level)
 
     def _set_autocommit(self, autocommit):
-        if self.psycopg2_version >= (2, 4, 2):
-            self.connection.autocommit = autocommit
-        else:
-            if autocommit:
-                level = psycopg2.extensions.ISOLATION_LEVEL_AUTOCOMMIT
+        with self.wrap_database_errors:
+            if self.psycopg2_version >= (2, 4, 2):
+                self.connection.autocommit = autocommit
             else:
-                level = self.isolation_level
-            self.connection.set_isolation_level(level)
+                if autocommit:
+                    level = psycopg2.extensions.ISOLATION_LEVEL_AUTOCOMMIT
+                else:
+                    level = self.isolation_level
+                self.connection.set_isolation_level(level)
 
     def check_constraints(self, table_names=None):
         """

django/db/backends/sqlite3/base.py

@@ -387,7 +387,8 @@ class DatabaseWrapper(BaseDatabaseWrapper):
             level = ''
         # 'isolation_level' is a misleading API.
         # SQLite always runs at the SERIALIZABLE isolation level.
-        self.connection.isolation_level = level
+        with self.wrap_database_errors:
+            self.connection.isolation_level = level
 
     def check_constraints(self, table_names=None):
         """