The latest stable of virtual/perl-DB_File (1.820) has this RDEPEND line: RDEPEND="|| ( ~dev-lang/perl-5.12.4 ~dev-lang/perl-5.12.3[berkdb] ~dev-lang/perl-5.12.2[berkdb] ~dev-lang/perl-5.12.1[berkdb] ~dev-lang/perl-5.10.1[berkdb] ~perl-core/DB_File-${PV} )" That means installing perl 5.12.4 fulfils that dependency and emerge --depclean will remove DB_File. However, perl 5.12.4 does not install DB_File, so one ends up with a system without DB_File.
@Hanno last time I've checked devs could assign their bugs ;)
Added [berkdb] once again. Thanks Hanno.