Created attachment 337788 [details] build.log see build.log
Created attachment 337790 [details] emerge --info
Does switching to Python2 solve the issue? root@host # eselect python set python2
Yep, solves it; builds fine with python 2.7
Try switching back to Python3, run python-updater, then try the emerge again.
Seems like a python-updater issue to me and not actually related to libpqxx.
I ran "python-updater -p -v" in the meantime, allowing myself to exclude libreoffice, scribus and geos from the rebuild since they take ages and geos would've pulled an older SLOT of php. One package failed but it was from the pro-audio overlay and needs to be fixed (not compatible with python-3.x yet). The other packages emerged just fine but the error is still the same when I try to emerge libpqxx with python-3.2 set as active version.
Created attachment 338858 [details] python-updater-log.txt Don't know if it's any help but here is the console log of python-updater and the following merges
03 May 2013; Aaron W. Swenson <titanofold@gentoo.org> libpqxx-4.0.1.ebuild: Inherit python-any-r1 to pull in a Python 2 interpreter. Use sed to fix shebangs to call python2 instead of python which could be set to a Python 3 interpreter. Fixes bug 455282.
