[packagekit] GetRequires and not-installed packages

[Richard Hughes]

Marcin has pointed out an ambiguity in the spec in
http://bugs.freedesktop.org/show_bug.cgi?id=14838.

The problem is that GetRequires (what packages depend on this one) could
be useful to find out what installed packages depend on this one (the
common case) but also for what available software in a repo depends on
this one.

Now, we have three options:

* Add a filter parameter to the method so we can differentiate between
installed and available
* Mandate that GetRequires will only operate on installed packages
* filter this in the client tools.

The third is least appealing for reasons I've pointed out in the
bugzilla, but I wanted your guys opinions on this. Is reverse searching
for deps in repos useful?

Thanks,

Richard.