biblatex.sty depends on iftex.sty, which is provided by dev-texlive/generic-extra.
I can confirm this.
Portage 2.2.28 (python 2.7.10-final-0, default/linux/amd64/13.0, gcc-4.9.3, glibc-2.22-r4, 4.4.6-gentoo x86_64) ================================================================= System uname: Linux-4.4.6-gentoo-x86_64-Intel-R-_Core-TM-_i3-2350M_CPU_@_2.30GHz-with-gentoo-2.2 KiB Mem: 3960360 total, 2879480 free KiB Swap: 2097148 total, 2097148 free Timestamp of repository gentoo: Wed, 14 Sep 2016 04:51:15 +0000 sh bash 4.3_p42-r1 ld GNU ld (Gentoo 2.25.1 p1.1) 2.25.1 app-shells/bash: 4.3_p42-r1::gentoo dev-lang/perl: 5.20.2::gentoo dev-lang/python: 2.7.10-r1::gentoo, 3.4.3-r1::gentoo dev-util/cmake: 3.5.2-r1::gentoo dev-util/pkgconfig: 0.28-r2::gentoo sys-apps/baselayout: 2.2::gentoo sys-apps/openrc: 0.21.3::gentoo sys-apps/sandbox: 2.10-r1::gentoo sys-devel/autoconf: 2.13::gentoo, 2.69::gentoo sys-devel/automake: 1.11.6-r1::gentoo, 1.14.1::gentoo, 1.15::gentoo sys-devel/binutils: 2.25.1-r1::gentoo sys-devel/gcc: 4.9.3::gentoo sys-devel/gcc-config: 1.7.3::gentoo sys-devel/libtool: 2.4.6::gentoo sys-devel/make: 4.1-r1::gentoo sys-kernel/linux-headers: 4.3::gentoo (virtual/os-headers) sys-libs/glibc: 2.22-r4::gentoo Repositories: gentoo location: /usr/portage sync-type: rsync sync-uri: rsync://127.0.0.1/gentoo-portage priority: -1000 lilrc location: /usr/local/lilrc-overlay masters: gentoo priority: 0 ACCEPT_KEYWORDS="amd64" ACCEPT_LICENSE="@FREE @MISC-FREE freedist" CBUILD="x86_64-pc-linux-gnu" CFLAGS="-O2 -fomit-frame-pointer -pipe -fno-stack-protector -mtune=generic" CHOST="x86_64-pc-linux-gnu" CONFIG_PROTECT="/etc /usr/share/gnupg/qualified.txt" CONFIG_PROTECT_MASK="/etc/ca-certificates.conf /etc/dconf /etc/env.d /etc/fonts/fonts.conf /etc/gconf /etc/gentoo-release /etc/revdep-rebuild /etc/sandbox.d /etc/terminfo /etc/texmf/language.dat.d /etc/texmf/language.def.d /etc/texmf/updmap.d /etc/texmf/web2c" CXXFLAGS="-O2 -fomit-frame-pointer -pipe -fno-stack-protector -mtune=generic" DISTDIR="/usr/portage/distfiles" EMERGE_DEFAULT_OPTS=" --binpkg-changed-deps=y --binpkg-respect-use=y --buildpkg-exclude app-admin/lilrc-update --buildpkg-exclude app-emulation/virtualbox-modules --buildpkg-exclude sys-fs/vhba --buildpkg-exclude sys-kernel/* --buildpkg-exclude virtual/*" FCFLAGS="-O2 -pipe" FEATURES="assume-digests binpkg-logs buildsyspkg config-protect-if-modified distlocks ebuild-locks fixlafiles ipc-sandbox merge-sync multilib-strict network-sandbox news noinfo parallel-fetch preserve-libs protect-owned sandbox sfperms strict unknown-features-warn unmerge-logs unmerge-orphans userfetch userpriv usersandbox usersync" FFLAGS="-O2 -pipe" GENTOO_MIRRORS="rsync://127.0.0.1/gentoo-portage/ http://distfiles.gentoo.org http://ftp.df.lth.se/pub/gentoo/ rsync://ftp.df.lth.se/pub/gentoo/ http://mirror.mdfnet.se/gentoo" INSTALL_MASK="/etc/systemd /usr/lib/systemd" LANG="C" LDFLAGS="-Wl,-O1 -Wl,--as-needed" MAKEOPTS="-j4" PKGDIR="/usr/portage/packages" PORTAGE_CONFIGROOT="/" PORTAGE_RSYNC_OPTS="--recursive --links --safe-links --perms --times --omit-dir-times --compress --force --whole-file --delete --stats --human-readable --timeout=180 --exclude=/distfiles --exclude=/local --exclude=/packages --exclude=/.git" PORTAGE_TMPDIR="/var/tmp" USE="X a52 aac alloca alsa amd64 aspell bluetooth cairo cd cdda cddb cdr cracklib crypt cups curl djvu dri drm dssi dvd dvdr dvi egl exif ffmpeg fftw flac fltk gallium gif gimp glib gmp gnuplot gnutls gstreamer gtk gtk2 gtkstyle gudev hwdb imap inotify javascript jit jpeg keymap ladspa lame libkms libnotify libsamplerate mad matplotlib mp3 mpeg netifrc networkmanager nptl octave ogg opengl openmp openrc orc pdf png policykit postscript qt4 qt5 readline sndfile spell ssl startup-notification subversion svg svn theora threads thunar tiff truetype udev udisks unicode upower usb v4l vaapi vdpau vlc vorbis webgl x264 xcb xcomposite xinerama xorg xscreensaver zlib" ABI_X86="64" CPU_FLAGS_X86="mmx sse sse2" CURL_SSL="gnutls" ELIBC="glibc" GRUB_PLATFORMS="pc" INPUT_DEVICES="evdev keyboard mouse synaptics" KERNEL="linux" LINGUAS="en en_GB" PYTHON_SINGLE_TARGET="python3_4" PYTHON_TARGETS="python2_7 python3_4" RUBY_TARGETS="ruby21" SANE_BACKENDS="plustek" USERLAND="GNU" VIDEO_CARDS="intel i915 i965 nouveau radeon" XFCE_PLUGINS="battery brightness power" Unset: CC, CPPFLAGS, CTARGET, CXX, LC_ALL, PORTAGE_BUNZIP2_COMMAND, PORTAGE_COMPRESS, PORTAGE_COMPRESS_FLAGS, PORTAGE_RSYNC_EXTRA_OPTS, USE_PYTHON
Fixed, thanks! commit 02371369312cf0b6cff2283235934ff21f1353dc Author: Manuel Rüger <mrueg@gentoo.org> Date: Mon Sep 26 21:52:33 2016 +0200 dev-tex/biblatex: Depend on dev-texlive/texlive-genericextra Gentoo-Bug: 585856 Package-Manager: portage-2.3.1