bitbake: serv/db: Take an excluside lock on the database

We only support one server using the database at a time so take an exclusive
lock and avoid later lock overhead.

(Bitbake rev: e3e39be6f2d063858c92971ce8ccd89c95d4f26d)

Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

bitbake/lib/prserv/db.py

@@ -224,7 +224,7 @@ class PRData(object):
         except OSError as e:
             if e.errno != errno.EEXIST:
                 raise e
-        self.connection=sqlite3.connect(self.filename, isolation_level="DEFERRED", check_same_thread = False)
+        self.connection=sqlite3.connect(self.filename, isolation_level="EXCLUSIVE", check_same_thread = False)
         self.connection.row_factory=sqlite3.Row
         self._tables={}