[O] outline-demote incorrectly demotes leaf nodes

[Sébastien Delafond]

Hello,

from Debian bug #645360 (http://bugs.debian.org/645360):

  Here's my test file, call it "c.org":

  * a
  ** aa
  *** aaa

  I put the cursor at the beginning of the file (at the * in the first
  line).  Then I type C-c C-> (i.e. outline-demote).  The result is

  ** a
  *** aa
  ***  aaa

  I expected that the last line (the leaf node "aaa") would become a
  fourth-level heading, i.e. "**** aaa".  Instead, the fourth * that I
  was hoping for looks like it became a space.

There wasn't any patch provided by the submitter.

Cheers,

--Seb