histedit: make errror message translatable

This is a follow up patch to https://phab.mercurial-scm.org/D2394
As suggested by Yuya, this patch makes the error message translatable

Differential Revision: https://phab.mercurial-scm.org/D3031

hgext/histedit.py

@@ -436,7 +436,7 b' class histeditaction(object):'
                 rulehash = _ctx.hex()
                 rev = node.bin(rulehash)
             except error.RepoLookupError:
-                raise error.ParseError("invalid changeset %s" % ruleid)
+                raise error.ParseError(_("invalid changeset %s") % ruleid)
         return cls(state, rev)
 
     def verify(self, prev, expected, seen):