revset: add test that should fail if '_aliasarg' tag is removed I'm going to refactor the alias processing functions. We need '_aliasarg' tag to limit the scope of the alias expansion, but it wasn't covered by the test. This patch adds the test that should fail if '_aliasarg' were 'symbol'. This is the first half of the second part of the "template alias" series. The whole series will consist of the following parts: 1. make parsed template tree to be compatible with parser functions (1d461ee26e1b and 73d01cba5810) 2. refactor alias processing to be less dependent on revset module (1/2 in this series) 3. extract reusable component to parser module 4. clean up it 5. extend it to support template syntax 6. add debugging/testing functions of template aliases 7. add alias expansion routine to templater