Fixes #1986: evil-open-fold fails to open folds in deeply nested outline/org headers

This commit fixes an issue in evil-mode where, in outline-mode or
org-mode, attempting to open a folded section (zo) fails when the cursor
is inside a deeply nested header. Previously, the fold would either not
expand or expand incorrectly, leaving the nested content hidden and
making navigation and editing of deeply nested structures difficult.

Author: jamescherti

evil-vars.el

@@ -1842,10 +1842,59 @@ Elements have the form (NAME . FUNCTION).")
      :close-all  ,(lambda ()
                     (with-no-warnings (hide-sublevels 1)))
      :toggle     outline-toggle-children
-     :open       ,(lambda ()
-                    (with-no-warnings
-                      (show-entry)
-                      (show-children)))
+     :open
+     ,(lambda ()
+        (save-excursion
+          (let (;; Invisible
+                (func-invisible-p
+                 (cond
+                  ;; `org-mode'
+                  ((and (derived-mode-p 'org-mode)
+                        (fboundp 'org-invisible-p))
+                   #'org-invisible-p)
+
+                  ;; `outline-mode' and `outline-minor-mode'
+                  ((and (or (derived-mode-p 'outline-mode)
+                            (bound-and-true-p outline-minor-mode))
+                        (fboundp 'outline-invisible-p))
+                   #'outline-invisible-p)))
+
+                ;; Back to heading
+                (func-back-to-heading
+                 (cond
+                  ;; `org-mode'
+                  ((and (derived-mode-p 'org-mode)
+                        (fboundp 'org-back-to-heading))
+                   #'org-back-to-heading)
+
+                  ;; `outline-mode' and `outline-minor-mode'
+                  ((and (or (derived-mode-p 'outline-mode)
+                            (bound-and-true-p outline-minor-mode))
+                        (fboundp 'outline-back-to-heading))
+                   #'outline-back-to-heading))))
+            (if (not (and func-back-to-heading
+                          func-invisible-p))
+                (with-no-warnings
+                  (show-entry)
+                  (show-children))
+              ;; Repeatedly reveal children and body until the entry is no
+              ;; longer folded
+              (condition-case nil
+                  ;; Repeatedly reveal children and body until the entry is no
+                  ;; longer folded
+                  (while (save-excursion
+                           ;; Folded?
+                           (funcall func-back-to-heading)
+                           (end-of-line)
+                           (funcall func-invisible-p (point)))
+                    (save-excursion
+                      (funcall func-back-to-heading)
+                      (with-no-warnings
+                        (show-children)
+                        (show-entry))))
+                ;; Ignore the `outline-back-to-heading' error
+                (outline-before-first-heading
+                 nil))))))
      :open-rec   show-subtree
      :close      hide-subtree)
     ((origami-mode)