ob-gnuplot.el (org-babel-gnuplot-quote-tsv-field): Fix code typo

* ob-gnuplot.el (org-babel-gnuplot-quote-tsv-field): Fix code typo.

TINYCHANGE

lisp/ob-gnuplot.el

@@ -253,7 +253,7 @@ then create one.  Return the initialized session.  The current
 	(org-babel-gnuplot-quote-timestamp-field s)
       (if (zerop (length s))
 	  (or *org-babel-gnuplot-missing* s)
-	(if (string-match "[ \"]" "?")
+	(if (string-match "[ \"]" s)
 	    (concat "\"" (mapconcat 'identity (split-string s "\"") "\"\"")
 		    "\"")
 	  s)))))