So the problem is due to lexical binding (I am using emacs 25 devel branch).
- pass them to eval as an environment.
Here is a patch for the second option, but I wonder if the first one wouldn't be better.
diff --git a/vendor/org-mode/lisp/ox-html.el b/vendor/org-mode/lisp/ox-html.el
index 6affac4..4e56ab3 100644
--- a/vendor/org-mode/lisp/ox-html.el
+++ b/vendor/org-mode/lisp/ox-html.el
@@ -3336,10 +3336,22 @@ communication channel."
;; Begin a rowgroup?
(when start-rowgroup-p (car rowgroup-tags))
;; Actual table row.
- (concat "\n" (eval (car (plist-get info :html-table-row-tags)) t)
+ (concat "\n" (eval (car (plist-get info :html-table-row-tags))
+ `((row-number . ,row-number)
+ (rowgroup-number . ,rowgroup-number)
+ (start-rowgroup-p . ,start-rowgroup-p)
+ (end-rowgroup-p . , end-rowgroup-p)
+ (top-row-p . ,top-row-p)
+ (bottom-row-p . ,bottom-row-p)))
contents
"\n"
- (eval (cdr (plist-get info :html-table-row-tags)) t))
+ (eval (cdr (plist-get info :html-table-row-tags))
+ `((row-number . ,row-number)
+ (rowgroup-number . ,rowgroup-number)
+ (start-rowgroup-p . ,start-rowgroup-p)
+ (end-rowgroup-p . , end-rowgroup-p)
+ (top-row-p . ,top-row-p)
+ (bottom-row-p . ,bottom-row-p))))
;; End a rowgroup?
(when end-rowgroup-p (cdr rowgroup-tags))))))