[Orgmode] Bug in HTML export of region with single heading?

[Adam Spiers]

When selecting a region containing a single tree for HTML export, the
tree head doesn't always become the document title.  For example, if I
select the tree via C-c @ (`outline-mark-subtree') then M-2 C-c C-e h,
it treats it as if it had more than one top-level heading.  But if I
then move the end of the region one character forward to the beginning
of the next line (`outline-mark-subtree' leaves it ending at the end
of the last line of the subtree, not the beginning of the next), and
do the same export, the document title is set correctly and so on.