sbuild stretch (... crossbuild-essential-armhf)

Hi!

I've been trying sbuild for strech:

sudo sbuild-createchroot
--make-sbuild-tarball=/srv/chroots/stretch-sbuild.tgz stretch
/srv/chroots/stretch http://httpredir.debian.org/debian/

This all seems to work and I've manually fetched a cross-toolchain:
  sudo sbuild-shell stretch-amd64-sbuild
  # apt-get install gcc-arm-linux-gnueabihf
  # apt-get install g++-arm-linux-gnueabihf gcc-arm-linux-gnueabihf

So far so good. (I'm not yet missing something here, or am I ?)

But then
  sbuild  --host=armhf -d stretch-amd64-sbuild
FAILS with:

  sbuild-build-depends-core-dummy : Depends:
crossbuild-essential-armhf but it is not installable
  E: Unable to correct problems, you have held broken packages.


That's a pitty! I see that crossbuild-essential-armhf is in sid, but
not in stretch.
Is there something I can do about that?
(Would creating an empty dummy package called
"crossbuild-essential-armhf" work? I'm running stretch.)

Thanks.