Strangely similar docstrings for mu4e

[Alessandro Bertulli <alessandro.bertulli96@gmail.com>]

Hi all!

Quick question. On my mu4e headers buffer, I see threads grouped with
characters like |, |>, L, o. I can get more or less the sense of them,
and they are usually very useful. However, my question is: what is the
difference between L and o? Using apropos I find:

mu4e-headers-thread-first-child-prefix
  Variable: Prefix for messages in sub threads that do not have a
            following sibling.
  Value: ("o " . "⚬ ")
  Properties: variable-documentation
mu4e-headers-thread-last-child-prefix
  Variable: Prefix for messages in sub threads that do not have a
            following sibling.
  Value: ("L" . "└ ")
  Properties: variable-documentation

Why are the two docstrings the same?

Alessandro