I've just released mgorny-dev-scripts 77, with a major revamp of pkgbump, integrating the trick from bump-boto and extending it.
Now you can pass a version increment as the second argument:
pkgbump foo-1.2.3.ebuild +1 (gives 1.2.4)
You can also increment a higher version by specifying the, then subsequent components:
pkgbump foo-1.2.3.ebuild +1.0 (gives 1.3.0)
(Yeah, sorry, that doesn't catch all possible variations but it's a side feature anyway.)
You can also pass a wildcard as the source, so that the newest (non-live) version is picked:
pkgbump 'django-5.2*.ebuild' +1
Or you can skip arguments and just do:
pkgbump +2 # the newest version +2
pkgbump # the newest version +1
Now I just need to use that to make bumping kernels much more pleasant.
#Gentoo