org-table-convert-refs-to-rc: Fix failing test

* lisp/org-table.el (org-table-convert-refs-to-an): Leave $0
references (current row) unchanged during conversion.
*
testing/lisp/test-org-table.el (test-org-table/org-table-convert-refs-to-an/2):
Re-enable the failing test.

lisp/org-table.el

@@ -3441,7 +3441,9 @@ full TBLFM line."
 (defun org-table-convert-refs-to-an (s)
   "Convert spreadsheet references from to @7$28 to AB7.
 Works for single references, but also for entire formulas and even the
-full TBLFM line."
+full TBLFM line.
+
+Leave the relative references unchanged."
   (while (string-match "@\\([0-9]+\\)\\$\\([0-9]+\\)" s)
     (setq s (replace-match
 	     (format "%s%d"
@@ -3449,7 +3451,7 @@ full TBLFM line."
 		      (string-to-number (match-string 2 s)))
 		     (string-to-number (match-string 1 s)))
 	     t t s)))
-  (while (string-match "\\(^\\|[^0-9a-zA-Z]\\)\\$\\([0-9]+\\)" s)
+  (while (string-match "\\(^\\|[^0-9a-zA-Z]\\)\\$\\([1-9][0-9]*\\)" s)
     (setq s (replace-match (concat "\\1"
 				   (org-number-to-letters
 				    (string-to-number (match-string 2 s))) "&")

testing/lisp/test-org-table.el

@@ -993,11 +993,10 @@ See also URL `https://orgmode.org/worg/org-tutorials/org-lookups.html'."
   (should
    (string= "A2" (org-table-convert-refs-to-an "@2$1"))))
 
-;; TODO: Test broken
-;; (ert-deftest test-org-table/org-table-convert-refs-to-an/2 ()
-;;   "Self reference @1$1."
-;;   (should
-;;    (string= "A1 = $0" (org-table-convert-refs-to-an "@1$1 = $0"))))
+(ert-deftest test-org-table/org-table-convert-refs-to-an/2 ()
+  "Self reference @1$1."
+  (should
+   (string= "A1 = $0" (org-table-convert-refs-to-an "@1$1 = $0"))))
 
 (ert-deftest test-org-table/org-table-convert-refs-to-an/3 ()
   "Remote reference."