We believe that your issue has been closed by the upload of
Version 0.78 of grml-debootstrap from Michael Prokop <mika@grml.org>.
The explanation is attached below

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Format: 1.8
Date: Thu, 26 Jan 2017 01:18:07 +0100
Source: grml-debootstrap
Binary: grml-debootstrap
Architecture: source all
Version: 0.78
Distribution: unstable
Urgency: medium
Maintainer: Grml Team <team@grml.org>
Changed-By: Michael Prokop <mika@grml.org>
Description:
 grml-debootstrap - wrapper around debootstrap for installing pure Debian
Changes:
 grml-debootstrap (0.78) unstable; urgency=medium
 .
   The "hello vienna, hello stretch" release
 .
   [ Evgeni Golov ]
   * [36a961d] don't fiddle around with /etc/hosts
 .
   [ Michael Prokop ]
   * [fdf85c6] Drop sysfsutils from default software package list
     [Closes: issue2240]
   * [622fa87] Don't generate rootfs entry in /etc/fstab if we
     don't know its UUID [Closes: issue2182]
   * [afccc8e] Debian stretch is the new default release
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 8dfacd88d9db9cf929538650dd2af1fe4ff83312 155044 grml-debootstrap_0.78.tar.xz
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Checksums-Sha256:
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Files:
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(This is bad because /media/sda1 is not a device, but a mountpoint.)

Command line:

grml-debootstrap --grub /dev/sda -t /media/sda1 -m http://http.at.debian.org/debian/ -r 
jessie --password XXX --bootappend "console=ttyS0,115200n8" --hostname XXX

Resulting fstab had:
/media/sda1 /  auto    defaults,errors=remount-ro 0   1