histedit: look up partial nodeid as partial nodeid

I'm about to remove support for repo[<partial hex nodeid>]. In the
verify() method, we know that self.node is always a partial or full
binary nodeid, so the most correct way to look up the revision is by
using changelog._partialmatch(), so let's do that. (It's closer to the
current code to do scmutil.revsymbol(), but that's less correct
because it will match a bookmark or tag that happens to have the same
prefix as the node.)

Differential Revision: https://phab.mercurial-scm.org/D3158

hgext/histedit.py

@@ -443,11 +443,9 b' class histeditaction(object):'
         """ Verifies semantic correctness of the rule"""
         repo = self.repo
         ha = node.hex(self.node)
-        try:
-            self.node = repo[ha].node()
-        except error.RepoError:
-            raise error.ParseError(_('unknown changeset %s listed')
-                              % ha[:12])
+        self.node = scmutil.resolvepartialhexnodeid(repo, ha)
+        if self.node is None:
+            raise error.ParseError(_('unknown changeset %s listed') % ha[:12])
         self._verifynodeconstraints(prev, expected, seen)
 
     def _verifynodeconstraints(self, prev, expected, seen):