It seems that org.el in org-20170821.tar is out of date. Sharon Kimble noticed that something was wrong, and after much digging, we found that org-clock.el has been updated to have calls to org-time-string-to-seconds with 2 arguments, but the function definition in org.el only takes 1 argument.
This is very strange, because the addition of the extra arg to org-time-string-to-seconds was made back on July 7, and that introduced a bug which was fixed in org-clock.el on August 5, yet the tarball from August 21 has the pre-July 7 org-time-string-to-seconds function. See https://github.com/Fuco1/org-clock-budget/issues/5#issuecomment-324331793 for more details.
