gh-61162: Clarify sqlite3 connection context manager docs

Doc/library/sqlite3.rst

@@ -1434,10 +1434,13 @@ case-insensitively by name:
 Using the connection as a context manager
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
-Connection objects can be used as context managers
-that automatically commit or rollback transactions. In the event of an
-exception, the transaction is rolled back; otherwise, the transaction is
-committed:
+With an open transaction, connection objects can be used as context managers
+that automatically commit or rollback transactions.
+If the body of the ``with`` statement finishes without exceptions,
+the transaction is committed.
+If an exception is raised and not caught, the transaction is rolled back.
+
+If there is no open transaction, the context manager is a no-op.
 
 .. literalinclude:: ../includes/sqlite3/ctx_manager.py
 

Misc/NEWS.d/next/Documentation/2022-06-16-10-10-59.gh-issue-61162.1ypkG8.rst

@@ -0,0 +1 @@
+Clarify :mod:`sqlite3` connection context manager behaviour.