[O] empty search causes infinite loop?

[Pete Siemsen]

I use Org mode version 8.2.10 under Aquamacs version 3.3 on Mac Sierra 10.12.3.

When I do "C-c a s" to search my org files for a keyword, it works
fine, except when I mistakenly search for nothing. In other words, if
when prompted for a search string, I hit RETURN, Aquamacs dives into
an infinite loop. I have to force-quit Aquamacs and restart.

-- Pete