Hi guys,

I've been using org-mode 7.9.3f for quite a bit time and for clocking
with unspecified timestamp I'd use the following construct:

 * Some task
   CLOCK: => 2:00

which was perfectly valid in this org-mode version. However, after
upgrading to 8.2.10, this isn't the case any more. As a matter of fact,
Emacs will throw this error when I try to export org file:

--->8---
Debugger entered--Lisp error: (wrong-type-argument stringp nil)
  string-match("[012]?[0-9]:[0-5][0-9]\\(-\\([012]?[0-9]\\):\\([0-5][0-9]\\)\\)" nil)
  org-element-timestamp-parser()
  org-element-clock-parser(649)
  org-element--current-element(649 nil nil nil)
  org-element--parse-elements(416 649 nil nil nil nil (section (:begin 416 :end 649 :contents-begin 416 :contents-end 649 :post-blank 0) (clock (:status closed :value (timestamp (:type inactive-range :raw-value $
  org-element--parse-elements(416 649 section nil nil nil (headline (:raw-value "Wed, 02" :begin 405 :end 649 :pre-blank 0 :hiddenp outline :contents-begin 416 :contents-end 649 :level 2 :priority nil :tags nil $
  org-element--parse-elements(243 2073 section nil nil nil (headline (:raw-value "December 2015" :begin 227 :end 2074 :pre-blank 0 :hiddenp outline :contents-begin 243 :contents-end 2073 :level 1 :priority nil :$
  org-element--parse-elements(1 25760 first-section nil nil nil (org-data nil (section (:begin 1 :end 211 :contents-begin 1 :contents-end 211 :post-blank 0 :parent #0) (keyword (:key "TITLE" :value "Timesheet" :$
  org-element-parse-buffer(nil nil)
  org-export-as(latex nil nil nil (:output-file "./placeavote-worklog.tex"))
  org-export-to-file(latex "./placeavote-worklog.tex" nil nil nil nil nil #[(file) "\301^H!\207" [file org-latex-compile] 2])
  org-latex-export-to-pdf(nil nil nil nil)
  org-export-dispatch(nil)
  call-interactively(org-export-dispatch nil nil)
  command-execute(org-export-dispatch)
---8<---

Looks like 'org-element-timestamp-parser' is always called while
exporting... Any idea how to return back old behavior (clock without
timestamp)?

Idea of clocks without timestamp is useful for me as for certain daily
tasks I'm mostly interested in total spent time, rather than precise
time. Beside, I also enters it manually after I forget to clock in,
which happens, well, often :)

Thanks!

Best regards,
Sanel