[O] N/A; icalendar export doesn't guarantee unique UIDs

[Tassilo Horn]

Remember to cover the basics, that is, what you expected to happen and
what in fact did happen.  You don't know how to make a good report?  See

     http://orgmode.org/manual/Feedback.html#Feedback

Your bug report will be posted to the Org-mode mailing list.
------------------------------------------------------------------------

I use the icalendar export to feed my schedule into the google calendar
(only one-way: Org -> Google).  Basically that works fine (except for
google not understanding Umlauts...), but there's a big problem with
entries that contain more than one timestamp.

For example, I have entries like

*** Meeting with Max
    :PROPERTIES:
    :ID:       e1c32cb4-bd1f-4302-8067-1723d1958a88
    :END:
    <2012-03-13 Tue 12:00-13:00>
    <2012-03-21 Wed 15:00-16:00>
    <2012-03-29 Thu 10:00-11:00>
    <2012-04-10 Tue 12:00-13:00>
    <2012-04-18 Wed 11:00-11:30>
    <2012-04-25 Wed 10:00-11:00>
    <2012-05-10 Thu 12:00-13:00>

They should show up at any date/time listed there.  That's true for the
org agenda with `org-agenda-skip-additional-timestamps-same-entry' set
to nil.  The icalendar export also creates multiple VEVENTS for the
above org entry, *but they all have the same UID* (which is strictly
VERBOTEN by the icalendar spec).  The result is that the google calendar
only shows one appointment, and that seems to be arbitrary.  In the
example above, it shows the meeting on 2012-04-18.

Bye,
Tassilo

Emacs  : GNU Emacs 24.1.50.1 (x86_64-pc-linux-gnu)
 of 2012-05-07 on thinkpad
Package: N/A

current state:
==============
(setq
 org-export-preprocess-before-selecting-backend-code-hook 
'(org-beamer-select-beamer-code)
 org-tab-first-hook '(org-hide-block-toggle-maybe
                      org-src-native-tab-command-maybe
                      org-babel-hide-result-toggle-maybe
                      org-babel-header-arg-expand)
 outline-minor-mode-hook '(th-outline-minor-mode-init)
 org-speed-command-hook '(org-speed-command-default-hook
                          org-babel-speed-command-hook)
 org-gnus-prefer-web-links t
 org-special-ctrl-k t
 org-occur-hook '(org-first-headline-recenter)
 org-src-tab-acts-natively t
 org-metaup-hook '(org-babel-load-in-session-maybe)
 org-icalendar-include-todo t
 org-export-preprocess-before-normalizing-links-hook 
'(org-remove-file-link-modifiers)
 org-log-done 'time
 org-confirm-shell-link-function 'yes-or-no-p
 org-complete-tags-always-offer-all-agenda-tags t
 org-finalize-agenda-hook '(th-org-agenda-to-appt)
 org-columns-default-format "%50ITEM %TODO %ALLTAGS %SCHEDULED %DEADLINE"
 org-export-latex-final-hook '(org-beamer-amend-header org-beamer-fix-toc
                               org-beamer-auto-fragile-frames
                               org-beamer-place-default-actions-for-lists)
 org-agenda-restore-windows-after-quit t
 org-special-ctrl-a/e 'reversed
 org-export-latex-after-initial-vars-hook '(org-beamer-after-initial-vars)
 org-agenda-custom-commands '(("n" "Next 21 days" agenda ""
                               ((org-agenda-span 21)))
                              ("^" "Calfw Month Calendar"
                               th-calfw-open-calendar)
                              )
 org-return-follows-link t
 org-agenda-time-leading-zero t
 org-capture-templates '(("n" "NORMAL" entry
                          (file "/home/horn/Repos/org/remember.org")
                          "* %?\n  :PROPERTIES:\n  :created: %U\n  :link: %a\n  
:END:\n %i")
                         ("t" "TODO" entry
                          (file "/home/horn/Repos/org/remember.org")
                          "* TODO %?\n  :PROPERTIES:\n  :created: %U\n  :link: 
%a\n  :END:\n  %i")
                         ("i" "IDEA" entry
                          (file "/home/horn/Repos/org/remember.org")
                          "* IDEA %?\n  :PROPERTIES:\n  :created: %U\n  :link: 
%a\n  :END:\n  %i")
                         )
 org-after-todo-state-change-hook '(org-clock-out-if-current)
 org-icalendar-include-body t
 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 '(th-org-mode-init
                 #[nil "\300\301\302\303\304$\207"
                   [org-add-hook change-major-mode-hook org-show-block-all
                    append local]
                   5]
                 #[nil "\300\301\302\303\304$\207"
                   [org-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-refile-targets '((org-agenda-files :maxlevel . 5))
 org-attach-method 'mv
 org-ctrl-c-ctrl-c-hook '(org-babel-hash-at-point
                          org-babel-execute-safely-maybe)
 org-refile-use-outline-path 'file
 org-directory "/home/horn/Repos/org"
 org-enforce-todo-dependencies t
 org-cycle-hook '(org-cycle-hide-archived-subtrees org-cycle-hide-drawers
                  org-cycle-show-empty-lines
                  org-optimize-window-after-visibility-change)
 org-export-latex-format-toc-function 'org-export-latex-format-toc-default
 org-export-blocks '((src org-babel-exp-src-block nil)
                     (export-comment org-export-blocks-format-comment t)
                     (ditaa org-export-blocks-format-ditaa nil)
                     (dot org-export-blocks-format-dot nil))
 org-export-first-hook '(org-beamer-initialize-open-trackers)
 org-attach-directory "/home/horn/Repos/org/attachments"
 org-icalendar-date-time-format ":%Y%m%dT%H%M%SZ"
 org-archive-default-command 'org-archive-set-tag
 org-export-interblocks '((src org-babel-exp-non-block-elements))
 org-refile-allow-creating-parent-nodes 'confirm
 org-icalendar-categories '(all-tags category)
 org-todo-keywords '((sequence "TODO(t)" "STARTED(s)" "DELEGATED(g)"
                      "IDEA(i)" "|" "DONE(d)" "CANCELLED(c)")
                     )
 org-modules '(org-icalendar org-attach org-protocol org-id org-bibtex
               org-docview org-gnus org-info org-irc org-capture
               org-mobile)
 org-confirm-elisp-link-function 'yes-or-no-p
 org-metadown-hook '(org-babel-pop-to-session-maybe)
 org-log-into-drawer "LOGBOOK"
 org-blocker-hook '(org-block-todo-from-children-or-siblings-or-parent)
 org-mobile-directory "~/Dropbox/MobileOrg"
 org-agenda-mode-hook '(th-org-agenda-mode-init)
 org-agenda-files '("/home/horn/Repos/org")
 org-clock-out-hook '(org-clock-remove-empty-clock-drawer)
 org-link-frame-setup '((vm . vm-visit-folder)
                        (gnus . org-gnus-no-new-news)
                        (file . find-file-other-window))
 org-mobile-inbox-for-pull "~/Repos/org/from-org-mobile.org"
 org-src-fontify-natively t
 )