bug#15568: Lookup this-command-keys without a prefix argument

[Juri Linkov]

> Here's an idea: check if (eq overriding-terminal-local-map isearch-mode-map)

I tried this approach and it passes my tests:

=== modified file 'lisp/isearch.el'
--- lisp/isearch.el     2013-10-09 23:52:46 +0000
+++ lisp/isearch.el     2013-10-11 23:49:42 +0000
@@ -2240,10 +2240,12 @@ (defun isearch-pre-command-hook ()
       (setq this-command 'isearch-edit-string))
      ;; Handle a scrolling function or prefix argument.
      ((or (and isearch-allow-prefix
-              (memq this-command '(universal-argument
-                                   universal-argument-more
-                                   universal-argument-minus
-                                   digit-argument negative-argument)))
+              (or (memq this-command '(universal-argument
+                                       digit-argument
+                                       negative-argument))
+                  ;; Check if a prefix arg added a nested map.
+                  (and overriding-terminal-local-map
+                       (not (eq overriding-terminal-local-map 
isearch-mode-map)))))
          (and isearch-allow-scroll
               (or (eq (get this-command 'isearch-scroll) t)
                   (eq (get this-command 'scroll-command) t))))