Revert "Disable aggressive locking for read-only SQLite databases."

This reverts commit fa5c840.

python/lsst/daf/butler/registry/databases/sqlite.py

@@ -50,6 +50,16 @@ def _onSqlite3Connect(
         cursor.execute("PRAGMA busy_timeout = 300000;")  # in ms, so 5min (way longer than should be needed)
 
 
+def _onSqlite3Begin(connection: sqlalchemy.engine.Connection) -> sqlalchemy.engine.Connection:
+    assert connection.dialect.name == "sqlite"
+    # Replace pysqlite's buggy transaction handling that never BEGINs with our
+    # own that does, and tell SQLite to try to acquire a lock as soon as we
+    # start a transaction (this should lead to more blocking and fewer
+    # deadlocks).
+    connection.execute(sqlalchemy.text("BEGIN IMMEDIATE"))
+    return connection
+
+
 class SqliteDatabase(Database):
     """An implementation of the `Database` interface for SQLite3.
 
@@ -180,16 +190,6 @@ def creator() -> sqlite3.Connection:
 
         engine = sqlalchemy.engine.create_engine(uri, creator=creator)
 
-        def _onSqlite3Begin(connection: sqlalchemy.engine.Connection) -> sqlalchemy.engine.Connection:
-            assert connection.dialect.name == "sqlite"
-            # Replace pysqlite's buggy transaction handling that never BEGINs
-            # with our own that does, and tell SQLite to try to acquire a lock
-            # as soon as we start a transaction (this should lead to more
-            # blocking and fewer deadlocks).
-            if writeable:
-                connection.execute(sqlalchemy.text("BEGIN IMMEDIATE"))
-            return connection
-
         sqlalchemy.event.listen(engine, "connect", _onSqlite3Connect)
         sqlalchemy.event.listen(engine, "begin", _onSqlite3Begin)