Created attachment 285275 [details] ebuild patch GUI provided by nmap with USE="gtk" installs Python modules that are not compiled. Attached patch to the ebuild fixes this for me.
first add your build failure
There is no build failure. It is installing .py files in: /usr/lib64/python2.7/site-packages/{radialnet,zenmapCore,zenmapGUI} and not creating .pyo and .pyc byte-compiled versions of them.
+*nmap-5.51.6 (25 Sep 2012) + + 25 Sep 2012; Sergey Popov <pinkbyte@gentoo.org> +nmap-5.51.6.ebuild: + Version bump with fix for bug #381469. Thanks to Chris Mayo for discovering + this issue