alias: test duplicated definition earlier This patch moves the old definition checking logic introduced by f4b7be3f8430 earlier. So that the test itself does not depend on `aliasdef`. The check is to avoid wrapping a same alias multiple times. It can be done by checking the config name and value (`definition` in code), without constructing a `cmdalias` instance. This makes the next patch easier to review. Differential Revision: https://phab.mercurial-scm.org/D804