[O] Bug: Bulk re-scheduling to a relative offset doesn't work [9.1.6 (9.1.6-48-gfe7619-elpa @ c:/Users/micha/.emacs.d/elpa/org-20180212/)]

[Michael Hoffman]

I previously asked a question about this on emacs-orgmode but it seems 
more likely that this is a bug.

https://lists.gnu.org/archive/html/emacs-orgmode/2018-02/msg00183.html

I am bulk re-scheduling items in an agenda view. I would like all the 
selected items to be re-scheduled to a year later from their current 
scheduled date. The org manual 
<https://orgmode.org/manual/Agenda-commands.html> seems to indicate this 
is possible using double plus:

> Schedule all items to a new date. To shift existing schedule dates by
> a fixed number of days, use something starting with double plus at the
> prompt, for example ‘++8d’ or ‘++2w’.

When I try this, however, I always get re-scheduling from the current 
date. I am using Org mode version 9.1.6 (9.1.6-48-gfe7619-elpa). Here's 
how to reproduce:

1. Create minimal.org.el:

(setq debug-on-error t
      debug-on-signal nil
      debug-on-quit nil)
(add-to-list 'load-path "c:/Users/micha/.emacs.d/elpa/org-20180212")

2. emacs.exe -Q -l minimal-org.el

3. Create a test.org buffer:

* TODO Task
  SCHEDULED: <2018-01-01 Mon>

4. Add it to the agenda files list with C-c [.

5. M-x org-agenda RET t results in

Global list of TODO items of type: ALL
Available with ‘N r’: (0)[ALL] (1)TODO (2)DONE
  test:       TODO Task

6. Move down to TODO Task and type m to mark

7. B s (bulk schedule). The minibuffer will state:

(Re)Schedule to Date+time [2018-02-11]: [cursor] => <2018-02-11 Sun>

8. ++1y. The right part of the minibuffer now states

<2019-02-11 Mon>

I expected <2019-01-01 Tue>

9. RET.

The task is now rescheduled to <2019-02-11 Mon> rather than <2019-01-01 
Tue> as initially expected.

Emacs  : GNU Emacs 25.2.1 (x86_64-w64-mingw32)
 of 2017-04-24
Package: Org mode version 9.1.6 (9.1.6-48-gfe7619-elpa @ 
c:/Users/micha/.emacs.d/elpa/org-20180212/)

current state:
==============
(setq
 org-tab-first-hook '(org-babel-hide-result-toggle-maybe
                      org-babel-header-arg-expand)
 org-speed-command-hook '(org-speed-command-activate
                          org-babel-speed-command-activate)
 org-occur-hook '(org-first-headline-recenter)
 org-metaup-hook '(org-babel-load-in-session-maybe)
 org-confirm-shell-link-function 'yes-or-no-p
 org-after-todo-state-change-hook '(org-clock-out-if-current)
 org-src-mode-hook '(org-src-babel-configure-edit-buffer
                     org-src-mode-configure-edit-buffer)
 org-agenda-before-write-hook '(org-agenda-add-entry-text)
 org-babel-pre-tangle-hook '(save-buffer)
 org-mode-hook '(#[0 "\300\301\302\303\304$\207"
                   [add-hook change-major-mode-hook org-show-block-all
                    append local]
                   5]
                 #[0 "\300\301\302\303\304$\207"
                   [add-hook change-major-mode-hook
                    org-babel-show-result-all append local]
                   5]
                 org-babel-result-hide-spec org-babel-hide-all-hashes)
 org-bibtex-headline-format-function #[257 "\300
\236A\207" [:title] 3 
"\n\n(fn ENTRY)"]
 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-confirm-elisp-link-function 'yes-or-no-p
 org-metadown-hook '(org-babel-pop-to-session-maybe)
 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") ("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)))
                        )
                       ("news" :follow
                        (lambda (path) (browse-url (concat "news:"; path))))
                       ("shell" :follow org--open-shell-link))
 org-clock-out-hook '(org-clock-remove-empty-clock-drawer)
 )