When you sometimes notice that {% url %} tag does not work for your named urls, then debugging it is easy. Start the python shell:
import app.views
from django.core.urlresolvers import reverse
reverse('named-view-to-be-tested')
If the view doesn’t work, it will either return NoReverseMatch: Not enough positional arguments passed in exception or url.
Thanks to jodal from #django for the tip.
As I needed a bit more recent kernel on one machine due to some exotic hardware, I didn’t want to use regular kernel provided by portage. Instead I opted to track latest Linus’s snapshot using git. Although there are snapshot kernel packages in the portage their usage is a bit cumbersome because every time new release is made and you update it, kernel sources will land into different directory… Managing these will become quite cumbersome… 
There was also another gotcha: removing all the kernels provided by portage made it unhappy as it wants to have at least one installed kernel. First I though I can just use the ‘–inject’ option to insert the package by not installing it, but unfortunately this feature has been removed ages ago
Fortunately the feature itself hadn’t been removed as it is possible to use either /etc/portage/package.mask or /etc/portage/profile/package.provided. package.mask isn’t suitable to use because there are some packages I use that depend on kernel package, so I had to use second option. But it took a while to figure out how to ignore all the versions because the package atom has to be provided with version number. So, in order to “inject” a package into system one has to use similar form:
sys-kernel/gentoo-sources-9999