emerge --color y --backtrack 9999 --update --deep --newuse --tree @world -vp

gistfile1.txt

480s /var/lib/portage # emerge --color y --backtrack 9999 --update --deep --newuse --tree @world -vp

These are the packages that would be merged, in reverse order:

Calculating dependencies... done!
[ebuild     U  ] sys-apps/systemd-240:0/2::gentoo [239-r2:0/2::gentoo] USE="acl gcrypt kmod lz4 pam pcre policykit resolvconf seccomp split-usr ssl sysv-utils -apparmor -audit -build -cryptsetup -curl -elfutils -gnuefi -http -idn -importd -libidn2 -lzma -nat -qrcode (-selinux) -test -vanilla -xkb" ABI_X86="(64) -32 (-x32)" 0 KiB
[ebuild     U  ] net-misc/wget-1.20.1::gentoo [1.20::gentoo] USE="ipv6 nls pcre ssl zlib -debug -gnutls -idn -libressl -ntlm -static -test -uuid" 0 KiB
[nomerge       ] gnome-base/gnome-3.30.2:2.0::Gnome-3-30-X  USE="bluetooth cdr classic extras -accessibility -cups" 
[nomerge       ]  gnome-base/gnome-extra-apps-3.30.2:3.0::Gnome-3-30-X  USE="games share shotwell tracker" 
[nomerge       ]   media-gfx/gnome-photos-3.30.1::Gnome-3-30-X  USE="-flickr -test -upnp-av" 
[nomerge       ]    net-libs/gnome-online-accounts-3.30.0:0/1::Gnome-3-30-X  USE="gnome introspection vala -debug -kerberos" 
[nomerge       ]     net-libs/webkit-gtk-2.22.4:4/37::gentoo  USE="X egl geolocation gstreamer introspection jit opengl webgl (-aqua) -coverage -doc -gles2 -gnome-keyring -libnotify -nsplugin -spell -test -wayland" 
[nomerge       ]      virtual/rubygems-15::gentoo [14::gentoo] RUBY_TARGETS="ruby24 ruby25 -ruby23 -ruby26% (-rbx%)" 
[ebuild   R    ]       dev-ruby/rubygems-3.0.1::gentoo  USE="-server -test" RUBY_TARGETS="ruby24 ruby25 -ruby23 -ruby26%" 0 KiB
[nomerge       ] dev-ruby/racc-1.4.14::gentoo  USE="-doc -test" RUBY_TARGETS="ruby24 ruby25 -ruby23 -ruby26%" 
[nomerge       ]  dev-lang/ruby-2.4.5-r1:2.4::gentoo  USE="berkdb gdbm ipv6 rdoc ssl -debug -doc -examples -jemalloc -libressl -rubytests -socks5 -static-libs -tk -xemacs" 
[ebuild     U  ]   dev-ruby/rdoc-6.1.0::gentoo [6.0.4::gentoo] USE="-doc -test" RUBY_TARGETS="ruby24 ruby25 -ruby23 -ruby26%" 0 KiB
[ebuild     U  ]   dev-ruby/json-2.1.0-r1:2::gentoo [2.1.0:2::gentoo] USE="-doc -test" RUBY_TARGETS="ruby24 ruby25 -ruby23 -ruby26%" 0 KiB
[ebuild   R    ]   dev-ruby/xmlrpc-0.3.0::gentoo  USE="-doc -test" RUBY_TARGETS="ruby24 ruby25 -ruby23 -ruby26%" 0 KiB
[ebuild   R    ]   dev-ruby/test-unit-3.2.9:2::gentoo  USE="-doc -test" RUBY_TARGETS="ruby24 ruby25 -ruby23 -ruby26%" 0 KiB
[ebuild   R    ]   dev-ruby/net-telnet-0.2.0:1::gentoo  USE="-doc -test" RUBY_TARGETS="ruby24 ruby25 -ruby23 -ruby26%" 0 KiB
[ebuild   R    ]   dev-ruby/minitest-5.11.3:5::gentoo  USE="-doc -test" RUBY_TARGETS="ruby24 ruby25 -ruby23 -ruby26%" 0 KiB
[nomerge       ] dev-ruby/kpeg-1.1.0-r1:1::gentoo  USE="-doc -test" RUBY_TARGETS="ruby24 ruby25 -ruby23 -ruby26%" 
[nomerge       ]  dev-lang/ruby-2.5.3:2.5::gentoo  USE="berkdb gdbm ipv6 rdoc ssl -debug -doc -examples -jemalloc -libressl -rubytests -socks5 -static-libs -tk -xemacs" 
[nomerge       ]   dev-ruby/rdoc-6.1.0::gentoo [6.0.4::gentoo] USE="-doc -test" RUBY_TARGETS="ruby24 ruby25 -ruby23 -ruby26%" 
[ebuild   R    ]    dev-ruby/racc-1.4.14::gentoo  USE="-doc -test" RUBY_TARGETS="ruby24 ruby25 -ruby23 -ruby26%" 0 KiB
[ebuild   R    ]    dev-ruby/kpeg-1.1.0-r1:1::gentoo  USE="-doc -test" RUBY_TARGETS="ruby24 ruby25 -ruby23 -ruby26%" 0 KiB
[ebuild   R    ]   dev-ruby/power_assert-1.1.3::gentoo  USE="-doc -test" RUBY_TARGETS="ruby24 ruby25 -ruby23 -ruby26%" 0 KiB
[ebuild   R    ]   dev-ruby/rake-12.3.2::gentoo  USE="-doc -test" RUBY_TARGETS="ruby24 ruby25 -ruby23 -ruby26%" 0 KiB
[ebuild     U  ]    virtual/rubygems-15::gentoo [14::gentoo] RUBY_TARGETS="ruby24 ruby25 -ruby23 -ruby26% (-rbx%)" 0 KiB
[nomerge       ] www-client/chromium-72.0.3626.28::gentoo  USE="hangouts (pic) proprietary-codecs suid -component-build -cups -custom-cflags -gnome-keyring -jumbo-build -kerberos (-neon) -pulseaudio (-selinux) (-system-ffmpeg) (-system-icu) (-system-libvpx) (-tcmalloc) -widevine" L10N="am ar bg bn ca cs da de el en-GB es es-419 et fa fi fil fr gu he hi hr hu id it ja kn ko lt lv ml mr ms nb nl pl pt-BR pt-PT ro ru sk sl sr sv sw ta te th tr uk vi zh-CN zh-TW" 
[ebuild  N     ]  net-libs/nodejs-8.15.0::gentoo  USE="icu inspector npm snapshot ssl -debug -doc -systemtap -test" CPU_FLAGS_X86="sse2" PYTHON_TARGETS="python2_7" 0 KiB

Total: 15 packages (5 upgrades, 1 new, 9 reinstalls), Size of downloads: 0 KiB

WARNING: One or more updates/rebuilds have been skipped due to a dependency conflict:

sys-libs/zlib:0

  (sys-libs/zlib-1.2.11-r2:0/1::gentoo, ebuild scheduled for merge) conflicts with
    sys-libs/zlib:0/1=[minizip] required by (www-client/chromium-72.0.3626.28:0/0::gentoo, installed)
                       ^^^^^^^ 
    >=sys-libs/zlib-1.2.8-r1:0/1=[abi_x86_32(-),abi_x86_64(-)] required by (dev-libs/libxml2-2.9.8:2/2::gentoo, installed)
                                                              
    >=sys-libs/zlib-1.2.8-r1:=[abi_x86_32(-),abi_x86_64(-)] required by (dev-libs/libxml2-2.9.8:2/2::gentoo, installed)
                                                           
    sys-libs/zlib:=[minizip] required by (www-client/chromium-72.0.3626.28:0/0::gentoo, installed)
                    ^^^^^^^ 

x11-libs/libxcb:0

  (x11-libs/libxcb-1.13.1:0/1.12::gentoo, ebuild scheduled for merge) conflicts with
    >=x11-libs/libxcb-1.10[abi_x86_64(-),xkb] required by (x11-libs/libxkbcommon-0.8.2:0/0::gentoo, installed)
                                         ^^^ 
    >=x11-libs/libxcb-1.10[xkb] required by (net-im/telegram-desktop-bin-1.5.4:0/0::gentoo, installed)
                           ^^^ 
    >=x11-libs/libxcb-1.10:=[xkb] required by (dev-qt/qtgui-5.11.3:5/5.11::gentoo, installed)
                             ^^^ 
    >=x11-libs/libxcb-1.10:0/1.12=[xkb] required by (dev-qt/qtgui-5.11.3:5/5.11::gentoo, installed)
                                   ^^^ 

x11-libs/gdk-pixbuf:2

  (x11-libs/gdk-pixbuf-2.36.12:2/2::gentoo, ebuild scheduled for merge) conflicts with
    x11-libs/gdk-pixbuf:2[jpeg,introspection] required by (media-video/cheese-3.30.0:0/8::Gnome-3-30-X, installed)
                          ^^^^               
    >=x11-libs/gdk-pixbuf-2.30.0:2[jpeg] required by (media-gfx/eog-3.28.4:1/1::Gnome-3-30-X, installed)
                                   ^^^^ 

app-text/xmlto:0

  (app-text/xmlto-0.0.28-r1:0/0::gentoo, ebuild scheduled for merge) conflicts with
    >=app-text/xmlto-0.0.26-r1[text(+)] required by (x11-misc/xdg-utils-1.1.3-r1:0/0::gentoo, installed)
                                       

media-libs/grilo:0.3

  (media-libs/grilo-0.3.6:0.3/0::gentoo, ebuild scheduled for merge) conflicts with
    >=media-libs/grilo-0.3.6:0.3/0=[network,playlist] required by (media-plugins/grilo-plugins-0.3.8:0.3/0.3::Gnome-3-30-X, installed)
                                            ^^^^^^^^ 
    >=media-libs/grilo-0.3.0:0.3[playlist] required by (media-video/totem-3.26.2:0/0::Gnome-3-30-X, installed)
                                 ^^^^^^^^ 
    >=media-libs/grilo-0.3.6:0.3=[network,playlist] required by (media-plugins/grilo-plugins-0.3.8:0.3/0.3::Gnome-3-30-X, installed)
                                          ^^^^^^^^ 

dev-libs/libgdata:0

  (dev-libs/libgdata-0.17.9-r1:0/22::gentoo, ebuild scheduled for merge) conflicts with
    >=dev-libs/libgdata-0.15.2:0=[crypt,gnome-online-accounts] required by (net-misc/gnome-online-miners-3.30.0:0/0::Gnome-3-30-X, installed)
                                        ^^^^^^^^^^^^^^^^^^^^^ 
    >=dev-libs/libgdata-0.15.2:0/22=[gnome-online-accounts] required by (media-gfx/gnome-photos-3.30.1:0/0::Gnome-3-30-X, installed)
                                     ^^^^^^^^^^^^^^^^^^^^^ 
    >=dev-libs/libgdata-0.13.3:=[crypt,gnome-online-accounts,introspection] required by (gnome-extra/gnome-documents-3.30.0:0/0::Gnome-3-30-X, installed)
                                       ^^^^^^^^^^^^^^^^^^^^^               
    >=dev-libs/libgdata-0.15.2:0/22=[crypt,gnome-online-accounts] required by (net-misc/gnome-online-miners-3.30.0:0/0::Gnome-3-30-X, installed)
                                           ^^^^^^^^^^^^^^^^^^^^^ 
    >=dev-libs/libgdata-0.15.2:0=[gnome-online-accounts] required by (media-gfx/gnome-photos-3.30.1:0/0::Gnome-3-30-X, installed)
                                  ^^^^^^^^^^^^^^^^^^^^^ 
    >=dev-libs/libgdata-0.13.3:0/22=[crypt,gnome-online-accounts,introspection] required by (gnome-extra/gnome-documents-3.30.0:0/0::Gnome-3-30-X, installed)
                                           ^^^^^^^^^^^^^^^^^^^^^               

sys-libs/tdb:0

  (sys-libs/tdb-1.3.16:0/0::gentoo, ebuild scheduled for merge) conflicts with
    >=sys-libs/tdb-1.3.16[python,abi_x86_64(-)] required by (sys-libs/ldb-1.4.3:0/1.4.3::gentoo, installed)
                          ^^^^^^               

sys-libs/tevent:0

  (sys-libs/tevent-0.9.37:0/0::gentoo, ebuild scheduled for merge) conflicts with
    >=sys-libs/tevent-0.9.37[python(+),abi_x86_64(-)] required by (sys-libs/ldb-1.4.3:0/1.4.3::gentoo, installed)
                                                     

app-crypt/pinentry:0

  (app-crypt/pinentry-1.1.0-r3:0/0::gentoo, ebuild scheduled for merge) conflicts with
    app-crypt/pinentry[gnome-keyring] required by (gnome-base/gnome-keyring-3.28.2-r2:0/0::Gnome-3-30-X, installed)
                       ^^^^^^^^^^^^^ 
    app-crypt/pinentry[gnome-keyring] required by (mail-client/evolution-3.30.3:2.0/2.0::Gnome-3-30-X, installed)
                       ^^^^^^^^^^^^^ 

media-libs/gst-plugins-base:1.0

  (media-libs/gst-plugins-base-1.14.4-r1:1.0/1.0::gentoo, ebuild scheduled for merge) conflicts with
    >=media-libs/gst-plugins-base-1.4:1.0[introspection,ogg,pango,theora,vorbis,X] required by (media-video/cheese-3.30.0:0/8::Gnome-3-30-X, installed)
                                                                  ^^^^^^          

media-libs/libjpeg-turbo:0

  (media-libs/libjpeg-turbo-2.0.1:0/0::gentoo, ebuild scheduled for merge) conflicts with
    >=media-libs/libjpeg-turbo-1.3.0-r3:0[abi_x86_32(-),abi_x86_64(-)] required by (virtual/jpeg-62:62/62::gentoo, installed)
                                                                      

virtual/libgudev:0

  (virtual/libgudev-232:0/0::gentoo, ebuild scheduled for merge) conflicts with
    virtual/libgudev:=[introspection] required by (media-gfx/shotwell-0.28.3:0/0::gentoo, installed)
                       ^^^^^^^^^^^^^ 
    virtual/libgudev:0/0=[introspection] required by (media-gfx/shotwell-0.28.3:0/0::gentoo, installed)
                          ^^^^^^^^^^^^^ 
    =virtual/libgudev-232[introspection] required by (media-gfx/shotwell-0.28.3:0/0::gentoo, installed)
                          ^^^^^^^^^^^^^ 

dev-libs/libgudev:0

  (dev-libs/libgudev-232:0/0::gentoo, ebuild scheduled for merge) conflicts with
    >=dev-libs/libgudev-232:0/0[abi_x86_64(-),introspection] required by (virtual/libgudev-232:0/0::gentoo, installed)