Bug: Removing and adding deadline bug in org agenda [9.1.9 (release_9.1.9-65-g5e4542 @ /usr/share/emacs/26.1/lisp/org/)]

[Benson Chu <bensonchu457@gmail.com>]

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I have a problem in org agenda. I have been able to reproduce this bug
in a simple environment. This is an example org file:

* TODO Task 1
<Already existing deadline>
* TODO Task 2

When I open org agenda, and I realize the deadline is far into the
past, I want to move the deadline to today. So, the easiest thing I can
think to do is C-u C-c C-d to remove the deadline, and then C-c C-d to
add the deadline again to make it today. However, when I do this, the
new deadline gets added to the task below, so I end up with something
like this:

* TODO Task 1
* TODO Task 2
<New deadline>

Is this the intended behavior? I think that org agenda expects the
deadline location to remain the same, but instead it gets removed, and
accidentally adds it to the next task, which is very annoying. A few
tasks of mine have disappeared into my large agenda file, and I've had
to go back digging through to re-find and deadline them because of
this. Are there any workarounds? Thanks!

Emacs : GNU Emacs 26.1 (build 1, x86_64-pc-linux-gnu, GTK+ Version 3.22.30)
of 2018-07-05
Package: Org mode version 9.1.9 (release_9.1.9-65-g5e4542 @ 
/usr/share/emacs/26.1/lisp/org/)

current state:
==============
(setq
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-metadown-hook '(org-babel-pop-to-session-maybe)
org-clock-out-hook '(org-clock-remove-empty-clock-drawer)
org-agenda-files '("/home/<my-name>/<my-sync-drive>/org/test/test-bug.org")
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-archive-hook '(org-attach-archive-delete-maybe)
org-confirm-elisp-link-function 'yes-or-no-p
org-agenda-before-write-hook '(org-agenda-add-entry-text)
org-metaup-hook '(org-babel-load-in-session-maybe)
org-bibtex-headline-format-function #[257 "\300.\236A\207" [:title] 3 
"\n\n(fn ENTRY)"]
org-babel-pre-tangle-hook '(save-buffer)
org-tab-first-hook '(org-babel-hide-result-toggle-maybe 
org-babel-header-arg-expand)
org-occur-hook '(org-first-headline-recenter)
org-cycle-hook '(org-cycle-hide-archived-subtrees org-cycle-hide-drawers 
org-cycle-show-empty-lines
org-optimize-window-after-visibility-change)
org-speed-command-hook '(org-speed-command-activate 
org-babel-speed-command-activate)
org-confirm-shell-link-function 'yes-or-no-p
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))
)