Ebuild is missing GENTOO_DEPEND_ON_PERL="no", see perl-module.eclass Same problem was fixed in collected ebuilds recently: bug #487406
It triggers unnecessary rebuild of subversion: # emerge -pv1 perl dev-perl/PlRPC dev-perl/WWW-RobotRules These are the packages that would be merged, in order: Calculating dependencies... done! [ebuild r U ] dev-lang/perl-5.16.3:0/5.16 [5.12.4-r1:0/0] USE="-berkdb -debug -doc -gdbm -ithreads (-build%)" 0 kB [ebuild U ] dev-perl/PlRPC-0.202.0-r1 [0.202.0] 0 kB [ebuild U ] dev-perl/WWW-RobotRules-6.10.0-r1 [6.10.0] 0 kB [ebuild rR ] dev-perl/HTTP-Cookies-6.0.1-r1 0 kB [ebuild rR ] dev-vcs/subversion-1.7.14 USE="dso nls vim-syntax webdav-neon -apache2 -berkdb -ctypes-python -debug -doc -extras -gnome-keyring -java -kde -perl -python -ruby -sasl {-test} -webdav-serf" PYTHON_TARGETS="python2_7 -python2_6" 0 kB
the 1.8 series got the fix some time ago, the 1.7 series now also got it with 1.7.17, which should be on your local rsync mirror in a few hours thanks for the report