histedit: correct output of error when 'base' is from the edit list

This was made more obvious by marmoute's recent rearrangement of this code.

hgext/histedit.py

@@ -789,9 +789,10 b' class base(histeditaction):'
     def _verifynodeconstraints(self, prev, expected, seen):
         # base can only be use with a node not in the edited set
         if self.node in expected:
-            msg = _('%s "%s" changeset was not an edited list candidate')
-            raise error.ParseError(msg % (self.verb, node.short(self.node)),
-                                   hint=_('only use listed changesets'))
+            msg = _('%s "%s" changeset was an edited list candidate')
+            raise error.ParseError(
+                msg % (self.verb, node.short(self.node)),
+                hint=_('base must only use unlisted changesets'))
 
 @action(['_multifold'],
         _(

tests/test-histedit-base.t

@@ -235,8 +235,8 b' base on a previously picked changeset'
   > base d273e35dcdf2 B
   > pick b2f90fd8aa85 I
   > EOF
-  hg: parse error: base "d273e35dcdf2" changeset was not an edited list candidate
-  (only use listed changesets)
+  hg: parse error: base "d273e35dcdf2" changeset was an edited list candidate
+  (base must only use unlisted changesets)
 
   $ hg --config experimental.histeditng=False histedit 5 --commands - 2>&1 << EOF | fixbundle
   > base cd010b8cd998 A