When columns view is opened with an "%Effort{:}" column, the sum is only
correct for the first parent element. Whereas "hours" are propagated up
the hierarchy, "days" are reset to zero when going up more than one
hierarchy.

Example:

* Level 1
** Level 2
*** Level 3
**** Level 4
:PROPERTIES:
:Effort:   2d
:END:

In columns view (with `# -*- org-time-clocksum-use-effort-durations: t;
org-time-clocksum-format: (:days "%dd " :require-days t :hours "%d"
:require-hours t :minutes ":%02d" :require-minutes t) -*-`) this only
reports correct effort values for Level 4 and Level 3. Level 1 and Level
2 show "0d 0:00", but "2d 0:00" is expected.




Emacs  : GNU Emacs 24.5.1 (i686-pc-mingw32)
 of 2015-04-11 on LEG570
Package: Org mode version 9.0 (9.0-elpa @ z:/.emacs.d/elpa/org-20161102/)

current state:
==============
(setq
 org-tab-first-hook '(org-babel-hide-result-toggle-maybe
		      org-babel-header-arg-expand)
 org-link-parameters '(("id" :follow org-id-open)
		       ("rmail" :follow org-rmail-open :store
			org-rmail-store-link)
		       ("mhe" :follow org-mhe-open :store org-mhe-store-link)
		       ("irc" :follow org-irc-visit :store org-irc-store-link)
		       ("info" :follow org-info-open :export org-info-export
			:store org-info-store-link)
		       ("gnus" :follow org-gnus-open :store
			org-gnus-store-link)
		       ("docview" :follow org-docview-open :export
			org-docview-export :store org-docview-store-link)
		       ("bibtex" :follow org-bibtex-open :store
			org-bibtex-store-link)
		       ("bbdb" :follow org-bbdb-open :export org-bbdb-export
			:complete org-bbdb-complete-link :store
			org-bbdb-store-link)
		       ("w3m" :store org-w3m-store-link) ("file+sys")
		       ("file+emacs")
		       ("ipynb" :follow ein:org-open :export nil)
		       ("doi" :follow org--open-doi-link)
		       ("elisp" :follow org--open-elisp-link)
		       ("file" :complete org-file-complete-link)
		       ("ftp" :follow
			(lambda (path) (browse-url (concat "ftp:" path))))
		       ("help" :follow org--open-help-link)
		       ("http" :follow
			(lambda (path) (browse-url (concat "http:" path))))
		       ("https" :follow
			(lambda (path) (browse-url (concat "https:" path))))
		       ("mailto" :follow
			(lambda (path) (browse-url (concat "mailto:" path))))
		       ("message" :follow
			(lambda (path) (browse-url (concat "message:" path))))
		       ("news" :follow
			(lambda (path) (browse-url (concat "news:" path))))
		       ("shell" :follow org--open-shell-link))
 org-archive-hook '(org-attach-archive-delete-maybe)
 org-cycle-hook '(org-cycle-hide-archived-subtrees org-cycle-hide-drawers
		  org-cycle-show-empty-lines
		  org-optimize-window-after-visibility-change)
 org-agenda-before-write-hook '(org-agenda-add-entry-text)
 org-confirm-babel-evaluate nil
 org-speed-command-hook '(org-speed-command-default-hook
			  org-babel-speed-command-hook)
 org-babel-pre-tangle-hook '(save-buffer)
 org-occur-hook '(org-first-headline-recenter)
 org-log-done 'note
 org-metaup-hook '(org-babel-load-in-session-maybe)
 org-confirm-elisp-link-function 'yes-or-no-p
 org-clock-out-hook '(org-clock-remove-empty-clock-drawer)
 org-mode-hook '(#[0 "\300\301\302\303\304$\207"
		   [add-hook change-major-mode-hook org-show-block-all append
		    local]
		   5 "\n\n(fn)"]
		 org-mode-reftex-setup
		 #[0 "\300\301\302\303\304$\207"
		   [add-hook change-major-mode-hook org-babel-show-result-all
		    append local]
		   5 "\n\n(fn)"]
		 org-babel-result-hide-spec org-babel-hide-all-hashes
		 turn-on-flyspell turn-on-auto-fill)
 org-src-preserve-indentation t
 org-metadown-hook '(org-babel-pop-to-session-maybe)
 org-startup-indented t
 org-agenda-files '("~/org/tasks.org")
 org-src-mode-hook '(org-src-babel-configure-edit-buffer
		     org-src-mode-configure-edit-buffer)
 org-after-todo-state-change-hook '(org-clock-out-if-current)
 org-babel-tangle-lang-exts '(("python" . "py") ("emacs-lisp" . "el")
			      ("elisp" . "el"))
 org-confirm-shell-link-function 'yes-or-no-p
 )