ports/102439: port upgrade: devel/monotone 0.29

[Lapo Luchini]

Pav Lucistnik wrote:
> Committed, thanks!
>
> PS I wasn't quite sure, what the unexec constructions in PLIST_FILES was ment
> to achieve, so I got rid of it.
It was meant to get rid of $PREFIX/share/zsh/site-functions directory
for people that don't use shells/zsh, while people that do use zsh
should have that directory (empty or not).
(it was inspired by similiar lines from sysutils/portupgrade/pkg-plist)