ob-R.el: Restore the handling of org-list in as var

* ob-R.el (org-babel-R-assign-elisp): Use the patch from
ccberry@health.ucsd.edu, to print org-list as a one column table as it
was the case in release_9.5. The break in R is due commit b4e437f96 *
ob-core: Resolve named list references to simple lists.

* test-ob-R.el (ob-R-nested-list): New function to test that org list
with multiple level are handled as expected in R.

see https://list.orgmode.org/87bkofh0ir.fsf@localhost/ for context.

lisp/ob-R.el

@@ -241,11 +241,11 @@ This function is called by `org-babel-execute-src-block'."
 (defun org-babel-R-assign-elisp (name value colnames-p rownames-p)
   "Construct R code assigning the elisp VALUE to a variable named NAME."
   (if (listp value)
-      (let* ((lengths (mapcar 'length (cl-remove-if-not 'sequencep value)))
+      (let* ((lengths (mapcar 'length (cl-remove-if-not 'listp value)))
 	     (max (if lengths (apply 'max lengths) 0))
 	     (min (if lengths (apply 'min lengths) 0)))
         ;; Ensure VALUE has an orgtbl structure (depth of at least 2).
-        (unless (listp (car value)) (setq value (list value)))
+        (unless (listp (car value)) (setq value (mapcar 'list value)))
 	(let ((file (orgtbl-to-tsv value '(:fmt org-babel-R-quote-tsv-field)))
 	      (header (if (or (eq (nth 1 value) 'hline) colnames-p)
 			  "TRUE" "FALSE"))

testing/lisp/test-ob-R.el

@@ -261,6 +261,41 @@ log10(10)
                     (string= (concat src-block result)
                              (buffer-string)))))))
 
+
+;; test for printing of (nested) list
+(ert-deftest ob-R-nested-list ()
+  "List are printed as the first column of a table and nested lists are ignored"
+  (let (ess-ask-for-ess-directory
+        ess-history-file
+        org-confirm-babel-evaluate
+        (org-babel-temporary-directory "/tmp")
+        (text "
+#+NAME: example-list
+- simple
+  - not
+  - nested
+- list
+
+#+BEGIN_SRC R :var x=example-list
+x
+#+END_SRC
+")
+(result "
+#+RESULTS:
+| simple |
+| list   |
+"))
+(org-test-with-temp-text-in-file
+    text
+  (goto-char (point-min))
+  (org-babel-next-src-block)
+  (should (progn  
+            (org-babel-execute-src-block)
+            (sleep-for 0 200)
+            (string= (concat text result)
+                     (buffer-string)))))))
+
+
 (provide 'test-ob-R)
 
 ;;; test-ob-R.el ends here