Hi,

I believe there is a bug in the preparation of a clock report when the
:step parameter is set.

Example:
========
* Headline 1
  :LOGBOOK:
  CLOCK: [2019-02-20 Wed 08:39]--[2019-02-20 Wed 14:05] =>  5:26
  CLOCK: [2019-02-19 Tue 13:38]--[2019-02-19 Tue 17:48] =>  4:10
  CLOCK: [2019-02-19 Tue 08:42]--[2019-02-19 Tue 12:40] =>  3:58
  CLOCK: [2019-02-18 Mon 15:34]--[2019-02-18 Mon 17:44] =>  2:10
  CLOCK: [2019-02-18 Mon 13:41]--[2019-02-18 Mon 14:48] =>  1:07
  CLOCK: [2019-02-18 Mon 08:32]--[2019-02-18 Mon 12:58] =>  4:26
  :END:

  Some text

  #+BEGIN: clocktable :scope file :maxlevel 2 :block thisweek :step week

  #+END:

Typing C-c C-c to refresh the table results in an error "invalid time
specification", failing on line 2738 of org-clock.el.

When I revert to org-9.2.0, the error is present, but when I revert to
org-9.1.9, the clocktable refreshes successfully.

Éibhear

Emacs  : GNU Emacs 24.4.1 (x86_64-pc-linux-gnu, GTK+ Version 3.14.5)
 of 2017-09-12 on hullmann, modified by Debian
Package: Org mode version 9.2.1 (9.2.1-dist @
/home/eibhear/eibhear_org/lisp/org-9/lisp/)

-- 
Éibhear Ó hAnluain
Dublin, Ireland.
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