First time submitting a bug here, so let me know if I am not following
protocol. I'm attaching the output of:

> sudo tar -vc --exclude=*.o --exclude=*/.deps/* --exclude=*/src/*
> --exclude=*/lib/* --exclude=*/distdir/* --exclude=*/man/*
> /var/tmp/portage/sys-apps/coreutils-8.20/ | xz --best >~/build-files.tar.xz
>
… which should include the build log (
/var/tmp/portage/sys-apps/coreutils-8.20/temp/build.log).

rgarrett@rgarrett ~ $ emerge --info '=sys-apps/coreutils-8.20'

> Portage 2.1.12.2 (default/linux/amd64/13.0/desktop/gnome, gcc-4.6.3,
> glibc-2.15-r3, 3.7.10-gentoo-r1 x86_64)
> =================================================================
>                          System Settings
> =================================================================
> System uname:
> Linux-3.7.10-gentoo-r1-x86_64-Intel-R-_Core-TM-2_Duo_CPU_T7250_@
> _2.00GHz-with-gentoo-2.2
> KiB Mem:     4004908 total,     43776 free
> KiB Swap:    2065404 total,   1381576 free
> Timestamp of tree: Sat, 29 Jun 2013 09:00:01 +0000
> ld GNU ld (GNU Binutils) 2.22
> app-shells/bash:          4.2_p45
> dev-java/java-config:     2.1.12-r1
> dev-lang/python:          2.7.3-r3, 3.2.3-r2
> dev-util/cmake:           2.8.10.2-r2
> dev-util/pkgconfig:       0.28
> sys-apps/baselayout:      2.2
> sys-apps/openrc:          0.11.8
> sys-apps/sandbox:         2.5
> sys-devel/autoconf:       2.13, 2.69
> sys-devel/automake:       1.9.6-r3, 1.10.3, 1.11.6, 1.12.6
> sys-devel/binutils:       2.22-r1
> sys-devel/gcc:            4.6.3
> sys-devel/gcc-config:     1.7.3
> sys-devel/libtool:        2.4-r1
> sys-devel/make:           3.82-r4
> sys-kernel/linux-headers: 3.7 (virtual/os-headers)
> sys-libs/glibc:           2.15-r3
> Repositories: gentoo
> ACCEPT_KEYWORDS="amd64"
> ACCEPT_LICENSE="* -@EULA"
> CBUILD="x86_64-pc-linux-gnu"
> CFLAGS="-march=core2 -O2 -pipe"
> CHOST="x86_64-pc-linux-gnu"
> CONFIG_PROTECT="/etc /usr/share/gnupg/qualified.txt
> /usr/share/maven-bin-3.0/conf"
> 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"
> CXXFLAGS="-march=core2 -O2 -pipe"
> DISTDIR="/usr/portage/distfiles"
> FCFLAGS="-O2 -pipe"
> FEATURES="assume-digests binpkg-logs candy config-protect-if-modified
> distlocks ebuild-locks fixlafiles merge-sync news parallel-fetch
> preserve-libs protect-owned sandbox sfperms strict test
> unknown-features-warn unmerge-logs unmerge-orphans userfetch userpriv
> usersync"
> FFLAGS="-O2 -pipe"
> GENTOO_MIRRORS="rsync://mirrors.rit.edu/gentoo/
> ftp://mirrors.rit.edu/gentoo/ http://mirrors.rit.edu/gentoo/
> http://ftp.ucsb.edu/pub/mirrors/linux/gentoo/
> ftp://ftp.ucsb.edu/pub/mirrors/linux/gentoo/ rsync://
> gentoo.cs.uni.edu/gentoo-distfiles http://gentoo.cs.uni.edu/
> http://mirror.usu.edu/mirrors/gentoo/"
> LANG="C"
> LDFLAGS="-Wl,-O1 -Wl,--as-needed"
> MAKEOPTS="-j2"
> PKGDIR="/usr/portage/packages"
> PORTAGE_CONFIGROOT="/"
> PORTAGE_RSYNC_OPTS="--recursive --links --safe-links --perms --times
> --compress --force --whole-file --delete --stats --human-readable
> --timeout=180 --exclude=/distfiles --exclude=/local --exclude=/packages"
> PORTAGE_TMPDIR="/var/tmp"
> PORTDIR="/usr/portage"
> PORTDIR_OVERLAY=""
> SYNC="rsync://rsync.gentoo.org/gentoo-portage"
> USE="X a52 aac acl acpi alsa amd64 berkdb bindist bluetooth branding bzip2
> cairo cdda cdr cli colord consolekit cracklib crypt cups cxx dbus dri dts
> dvd dvdr eds emacs emboss encode evo exif fam firefox flac fortran gdbm gif
> gnome gnome-keyring gnome-online-accounts gpm gstreamer gtk iconv ipv6 jpeg
> lcms ldap libnotify libsecret mad mmx mng modules mp3 mp4 mpeg mudflap
> multilib nautilus ncurses nls nptl ogg opengl openmp pam pango pcre pdf png
> policykit ppds pulseaudio qt3support qt4 readline sdl session socialweb
> spell sse sse2 ssl startup-notification svg tcpd tiff truetype udev udisks
> unicode upower usb vorbis wxwidgets x264 xcb xml xv xvid zlib" ABI_X86="64"
> ALSA_CARDS="ali5451 als4000 atiixp atiixp-modem bt87x ca0106 cmipci
> emu10k1x ens1370 ens1371 es1938 es1968 fm801 hda-intel intel8x0 intel8x0m
> maestro3 trident usb-audio via82xx via82xx-modem ymfpci"
> APACHE2_MODULES="authn_core authz_core socache_shmcb unixd actions alias
> auth_basic authn_alias authn_anon authn_dbm authn_default authn_file
> authz_dbm authz_default authz_groupfile authz_host authz_owner authz_user
> autoindex cache cgi cgid dav dav_fs dav_lock deflate dir disk_cache env
> expires ext_filter file_cache filter headers include info log_config logio
> mem_cache mime mime_magic negotiation rewrite setenvif speling status
> unique_id userdir usertrack vhost_alias" CALLIGRA_FEATURES="kexi words flow
> plan sheets stage tables krita karbon braindump author" CAMERAS="ptp2"
> COLLECTD_PLUGINS="df interface irq load memory rrdtool swap syslog"
> CURL_SSL="openssl" ELIBC="glibc" GPSD_PROTOCOLS="ashtech aivdm earthmate
> evermore fv18 garmin garmintxt gpsclock itrax mtk3301 nmea ntrip navcom
> oceanserver oldstyle oncore rtcm104v2 rtcm104v3 sirf superstar2 timing tsip
> tripmate tnt ubx" INPUT_DEVICES="evdev" KERNEL="linux" LCD_DEVICES="bayrad
> cfontz cfontz633 glk hd44780 lb216 lcdm001 mtxorb ncurses text"
> LIBREOFFICE_EXTENSIONS="presenter-console presenter-minimizer"
> OFFICE_IMPLEMENTATION="libreoffice" PHP_TARGETS="php5-3"
> PYTHON_SINGLE_TARGET="python2_7" PYTHON_TARGETS="python2_7 python3_2"
> RUBY_TARGETS="ruby19 ruby18" USERLAND="GNU" VIDEO_CARDS="intel"
> XTABLES_ADDONS="quota2 psd pknock lscan length2 ipv4options ipset ipp2p
> iface geoip fuzzy condition tee tarpit sysrq steal rawnat logmark ipmark
> dhcpmac delude chaos account"
> Unset:  CPPFLAGS, CTARGET, EMERGE_DEFAULT_OPTS, INSTALL_MASK, LC_ALL,
> PORTAGE_BUNZIP2_COMMAND, PORTAGE_COMPRESS, PORTAGE_COMPRESS_FLAGS,
> PORTAGE_RSYNC_EXTRA_OPTS, USE_PYTHON
>
> =================================================================
>                         Package Settings
> =================================================================
>
> sys-apps/coreutils-8.20 was built with the following:
> USE="acl (multilib) nls -caps -gmp (-selinux) -static -vanilla -xattr"
> ABI_X86="64"
> CFLAGS="-O2 -pipe"
> CXXFLAGS="-O2 -pipe"
>

rgarrett@rgarrett ~ $ emerge -pqv '=sys-apps/coreutils-8.20'

> [ebuild   R   ] sys-apps/coreutils-8.20  USE="acl nls -caps -gmp
> (-selinux) -static -vanilla -xattr"
>