Fix issue #439; bug report and fix both submitted by Yoshiki Hayashi <yoshiki@xemacs.org>:
Fix issue #439; bug report and fix both submitted by Yoshiki Hayashi
<yoshiki@xemacs.org>:

* questions.c (timestamps_equal_p): Check for null entry.


git-svn-id: f8a4e5e023278da1e04e203c7fe051e3c4285d88@839952 13f79535-47bb-0310-9956-ffa450edef68

wbond/subversion,YueLinHo/Subversion,YueLinHo/Subversion,YueLinHo/Subversion,YueLinHo/Subversion,wbond/subversion,wbond/subversion,YueLinHo/Subversion,YueLinHo/Subversion,wbond/subversion,YueLinHo/Subversion,wbond/subversion,YueLinHo/Subversion,wbond/subversion,wbond/subversion