revert: explicitly get status against the parent

This makes absolutely no functional changes. The default value for
node1 is already the same as the current value of parent. But to be
able to properly use the second parent in merge context, we have to
start to be a bit more explicit about what we compute the status
against.

mercurial/cmdutil.py

@@ -2298,7 +2298,7 b' def revert(ui, repo, ctx, parents, *pats'
 
         # Find status of all file in `names`. (Against working directory parent)
         m = scmutil.matchfiles(repo, names)
-        changes = repo.status(match=m)[:4]
+        changes = repo.status(node1=parent, match=m)[:4]
         modified, added, removed, deleted = map(set, changes)
 
         # if f is a rename, update `names` to also revert the source