Fix previous gdb-mi change.

lisp/progmodes/gdb-mi.el

@@ -671,8 +671,10 @@ detailed description of this mode.
 				    (file-name-directory file))))
 		      ((string-equal (match-string 1) "size")
 		       (setq hsize (match-string 2))))))))
-      (if (integerp hsize)
-	  (set (make-local-variable 'comint-input-ring-size) hsize))
+      (and (stringp hsize)
+	   (integerp (string-to-number hsize))
+	   (> hsize 0)
+	   (set (make-local-variable 'comint-input-ring-size) hsize))
       (if (stringp hfile)
 	  (set (make-local-variable 'comint-input-ring-file-name) hfile))
       (comint-read-input-ring t)))