sed sources from git://git.sv.gnu.org/sed

I could not find any autogen.sh nor configure.
All the usual tools trigger error(s):

git-sed# export ACLOCAL_AMFLAGS="-I m4"
git-sed# autoreconf -v --install
autoreconf: Entering directory `.'
autoreconf: running: autopoint
Copying file ABOUT-NLS
...
Copying file po/remove-potcdate.sin
autoreconf: running: aclocal 
sh: 1: build-aux/git-version-gen: not found
configure.ac:24: error: AC_INIT should be called with package and version arguments
/usr/share/aclocal-1.15/init.m4:29: AM_INIT_AUTOMAKE is expanded from...
configure.ac:24: the top level
autom4te: /usr/bin/m4 failed with exit status: 1
aclocal: error: echo failed with exit status: 1
autoreconf: aclocal failed with exit status: 1

or:

git-sed# git-reset-clean-pull-checkout.sh master
git-sed# autoconf
sh: 1: build-aux/git-version-gen: not found
configure.ac:22: error: possibly undefined macro: AM_CONFIG_HEADER
      If this token and others are legitimate, please use m4_pattern_allow.
      See the Autoconf documentation.
configure.ac:24: error: possibly undefined macro: AM_INIT_AUTOMAKE
configure.ac:26: error: possibly undefined macro: AM_SILENT_RULES
configure.ac:30: error: possibly undefined macro: AM_PROG_CC_C_O
configure.ac:105: error: possibly undefined macro: AM_GNU_GETTEXT_VERSION
configure.ac:106: error: possibly undefined macro: AM_GNU_GETTEXT
configure.ac:116: error: possibly undefined macro: AM_CONDITIONAL

How are we supposed to build configure?

--
Jean-Christophe