This is on Funtoo, using ebuilds for Gentoo. So I figured to report the bug here. I think that boto needs its dependency on virtual/python-json to be removed.
# emerge -vua1 dev-python/boto
These are the packages that would be merged, in order:
Calculating dependencies... done!
[ebuild N #] virtual/python-json-1000 USE="external" PYTHON_ABIS="2.7 3.3 -2.5 -2.5-jython -2.6 -2.7-jython -2.7-pypy-1.9 -2.7-pypy-2.0 -3.1 -3.2 (-3.4)" 0 kB
[ebuild U ] dev-python/boto-2.13.0-r1000 [2.10.0-r1000] PYTHON_ABIS="2.7 -2.6" 1,032 kB
Total: 2 packages (1 upgrade, 1 new), Size of downloads: 1,032 kB
The following mask changes are necessary to proceed:
(see "package.unmask" in the portage(5) man page for more details)
# required by dev-python/boto-2.13.0-r1000
# required by dev-python/boto (argument)
# Michał Górny <email@example.com> (12 Sep 2013)
# All currently supported Python implementations have built-in json
# module already. This renders the virtual no longer needed. Please
# remove your dependencies on it and enjoy json out-of-the-box.
# Removal in 30 days.
We don't have that ebuild.