Pseudo-Portname Selectors

[Joshua Root]

> When I run
>
> port echo depends:vim
>
> neovim-qt
> p5-text-vimcolor
> py-neovim
> rails.vim
> libvmaf
> gutils-suite-core
> mpvim
> neovim-remote
> nvimpager
> vim2html
> vimpager
> dosfstools
>
> (12 ports are listed)
>
> But when I run
>
> port echo rdepends:vim
>
> dosfstools
> gutils-suite
> gutils-suite-core
> gutils-suite-extra
> libvmaf
> mpvim
> rails.vim
> vim2html
> vimpager
>
> (9 ports are listed)

Another subtle semantic difference. The selectors that match against the 
PortIndex do so as a regex. But for rdepends:, there isn't really any 
sensible way to apply the same regex recursively, since the string you 
want to match changes with each level of recursion. So it just does 
exact string matching on the portname component of each depspec.

Due to depends: taking a regex that is matched on the raw PortIndex 
fields, the way to get all ports that directly depend on vim is actually:

port echo 'depends::vim(\s|$)'

because the regex "vim" will match other ports like neovim and vimpager.

- Josh