tests: avoid deprecation warning

tests/test-devel-warnings.t

@@ -13,6 +13,8 b''
   >     tr = repo.transaction('buggy')
   >     lo = repo.lock()
   >     wl = repo.wlock()
+  >     wl.release()
+  >     lo.release()
   > EOF
 
   $ cat << EOF >> $HGRCPATH