The problem is that sync-type=git in repos.conf obliviously requires git installed, but git could not be installed before first sync. It forces to make two full syncs during instalation, if git repo is preferred
FYI with default USE flags this would add 45 new pkgs to stage3 (25 real, 20 perl virtuals). [ebuild N ] dev-libs/libgpg-error-1.27-r1 USE="nls -common-lisp -static-libs" ABI_X86="(64) -32 (-x32)" [ebuild N ] virtual/perl-ExtUtils-MakeMaker-7.100.200_rc-r2 [ebuild N ] dev-libs/libunistring-0.9.7 USE="-doc -static-libs" ABI_X86="(64) -32 (-x32)" [ebuild N ] virtual/perl-CPAN-Meta-YAML-0.18.0-r2 [ebuild N ] virtual/perl-Parse-CPAN-Meta-1.441.700.100_rc-r2 [ebuild N ] virtual/perl-Scalar-List-Utils-1.420.200_rc-r1 [ebuild N ] dev-libs/npth-1.3 USE="-static-libs" [ebuild N ] app-eselect/eselect-lib-bin-symlink-0.1.1 [ebuild N ] dev-libs/nettle-3.3-r2 USE="gmp -doc (-neon) -static-libs {-test}" ABI_X86="(64) -32 (-x32)" CPU_FLAGS_X86="-aes" [ebuild N ] dev-perl/Locale-gettext-1.50.0-r1 [ebuild N ] virtual/perl-Digest-SHA-5.950.100_rc-r4 [ebuild N ] virtual/perl-Digest-MD5-2.540.0-r3 [ebuild N ] virtual/perl-Text-ParseWords-3.300.0-r3 [ebuild N ] virtual/perl-Perl-OSType-1.9.0-r1 [ebuild N ] virtual/perl-Module-Metadata-1.0.31-r1 [ebuild N ] virtual/perl-Getopt-Long-2.480.0-r1 [ebuild N ] virtual/perl-ExtUtils-ParseXS-3.310.0-r1 [ebuild N ] virtual/perl-ExtUtils-Manifest-1.700.0-r4 [ebuild N ] virtual/perl-ExtUtils-Install-2.40.0-r3 [ebuild N ] virtual/perl-ExtUtils-CBuilder-0.280.225-r2 [ebuild N ] virtual/perl-JSON-PP-2.273.0.100_rc-r4 [ebuild N ] virtual/perl-version-0.991.600-r1 [ebuild N ] virtual/perl-MIME-Base64-3.150.0-r3 [ebuild N ] virtual/perl-libnet-3.80.100_rc-r2 [ebuild N ] virtual/yacc-0 [ebuild N ] net-misc/curl-7.55.1 USE="ipv6 ssl -adns -http2 -idn -kerberos -ldap -metalink -rtmp -samba -ssh -static-libs {-test} -threads" ABI_X86="(64) -32 (-x32)" CURL_SSL="openssl -axtls -gnutls (-libressl) -mbedtls -nss (-winssl)" [ebuild N ] dev-libs/libassuan-2.4.3-r1 USE="-static-libs" [ebuild N ] dev-libs/libgcrypt-1.8.1 USE="-doc -static-libs" ABI_X86="(64) -32 (-x32)" [ebuild N ] sys-apps/help2man-1.47.4 USE="nls" [ebuild N ] dev-libs/libksba-1.3.5-r1 USE="-static-libs" [ebuild N ] app-eselect/eselect-pinentry-0.7 [ebuild N ] dev-perl/Net-SSLeay-1.810.0 USE="-examples (-libressl) -minimal {-test}" [ebuild N ] dev-perl/Digest-HMAC-1.30.0-r1 [ebuild N ] virtual/perl-CPAN-Meta-2.150.5-r1 [ebuild N ] dev-perl/Authen-SASL-2.160.0-r1 USE="-kerberos" [ebuild N ] app-crypt/pinentry-0.9.7-r1 USE="ncurses -caps -emacs -gnome-keyring -gtk -qt4 -qt5 -static" [ebuild N ] dev-libs/libtasn1-4.12-r1 USE="-doc -static-libs -valgrind" ABI_X86="(64) -32 (-x32)" [ebuild N ] net-dns/libidn2-2.0.4 USE="-static-libs" ABI_X86="(64) -32 (-x32)" [ebuild N ] dev-perl/IO-Socket-SSL-2.24.0 USE="-idn" [ebuild N ] dev-perl/Module-Build-0.421.600 USE="{-test}" [ebuild N ] dev-perl/Error-0.170.240 USE="{-test}" [ebuild N ] dev-perl/Net-SMTP-SSL-1.30.0 USE="{-test}" [ebuild N ] net-libs/gnutls-3.5.15 USE="cxx idn nls openssl seccomp tls-heartbeat zlib -dane -doc -examples -guile -openpgp -pkcs11 -sslv2 -sslv3 -static-libs {-test} (-test-full) -tools -valgrind" ABI_X86="(64) -32 (-x32)" LINGUAS="-cs -de -en -fi -fr -it -ms -nl -pl -sv -uk -vi -zh_CN" [ebuild N ] app-crypt/gnupg-2.1.20-r1 USE="bzip2 gnutls nls readline smartcard -doc -ldap (-selinux) -tofu -tools -usb -wks-server" [ebuild N ] dev-vcs/git-2.13.6 USE="blksha1 curl gpg iconv nls pcre perl python threads webdav -cgi -cvs -doc -emacs -gnome-keyring -highlight (-libressl) -mediawiki -mediawiki-experimental (-ppcsha1) -subversion {-test} -tk -xinetd" LINGUAS="-bg -ca -de -fr -is -it -ko -pt_PT -ru -sv -vi -zh_CN" PYTHON_TARGETS="python2_7"
Until git becomes a system dependency or we move to a git distribution model, I'm going to close it as WONTFIX.