We believe that your issue has been closed by the upload of
Version 0.39 of grml-debootstrap from Michael Prokop <mika@grml.org>.
The explanation is attached below

-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1

Format: 1.8
Date: Mon, 18 Oct 2010 14:51:16 +0200
Source: grml-debootstrap
Binary: grml-debootstrap
Architecture: source all
Version: 0.39
Distribution: unstable
Urgency: low
Maintainer: Michael Prokop <mika@grml.org>
Changed-By: Michael Prokop <mika@grml.org>
Description: 
 grml-debootstrap - wrapper around debootstrap for installing plain Debian via grml
Changes: 
 grml-debootstrap (0.39) unstable; urgency=low
 .
   [ Tong Sun ]
   * remove 'umount -a' in bailout(). [Closes: issue806].
 .
   [ Christian Hofstaedtler ]
   * Remove "read -s" bashism from target chroot script.
     [Closes: issue912].
 .
   [ Michael Prokop ]
   * Bump Standards-Version to 3.9.1.
Checksums-Sha1: 
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 697dd14215d1741a3caccadde757f9f041879275 138398 grml-debootstrap_0.39.tar.gz
 ca499897463148d3d0a004bed300a44f6f50a877 113322 grml-debootstrap_0.39_all.deb
Checksums-Sha256: 
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 648b0911d529860a11be94bc998d5a8c280076017e9da6c16fa1c500203e5b4a 113322 grml-debootstrap_0.39_all.deb
Files: 
 61b281d9968793848539a67ba6fd9952 992 grml optional grml-debootstrap_0.39.dsc
 8b929f2178174f56ea73453e97705fbd 138398 grml optional grml-debootstrap_0.39.tar.gz
 f202be5d7ca4c960e699ca076f1307e3 113322 grml optional grml-debootstrap_0.39_all.deb

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---------- Forwarded message ----------
From: Tong Sun <suntong at cpan.org>
Date: Tue, Jun 8, 2010 at 5:50 PM
Subject: [PATCH] [issue806] final fix
To: grml-devel@ml.grml.org

remove 'umount -a',see
http://bts.grml.org/grml/issue806
---
 grml-debootstrap |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/grml-debootstrap b/grml-debootstrap
index dc4006d..f9b5ebb 100755
--- a/grml-debootstrap
+++ b/grml-debootstrap
@@ -644,7 +644,7 @@ bailout(){
        [ -x "$MNTPOINT"/etc/init.d/ssh   ] && "$MNTPOINT"/etc/init.d/ssh
stop
        [ -x "$MNTPOINT"/etc/init.d/mdadm ] && "$MNTPOINT"/etc/init.d/mdadm
stop
        # ugly, but make sure we really don't leave anything (/proc /proc is
intended)
-        for ARG in /sys -a /proc /proc ; do
+        for ARG in /sys /proc /proc ; do
          [ -x "$MNTPOINT"/bin/umount ] && chroot "$MNTPOINT" umount $ARG
>/dev/null 2>&1 || true
        done
        umount "$MNTPOINT"/dev >/dev/null 2>&1 || true
--
1.7.1

We believe that your issue has been closed by the upload of
Version 0.35 of grml-debootstrap from Michael Prokop <mika@grml.org>.
The explanation is attached below

-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1

Format: 1.8
Date: Fri, 26 Feb 2010 15:19:10 +0100
Source: grml-debootstrap
Binary: grml-debootstrap
Architecture: source all
Version: 0.35
Distribution: unstable
Urgency: low
Maintainer: Michael Prokop <mika@grml.org>
Changed-By: Michael Prokop <mika@grml.org>
Description: 
 grml-debootstrap - wrapper around debootstrap for installing plain Debian via grml
Changes: 
 grml-debootstrap (0.35) unstable; urgency=low
 .
   * Do NOT execute 'umount -a' in chroot script for cleanup. This
     can cause problems with installations to directories.
     Thanks for the bugreport and debugging, Tong Sun.
     [Closes: issue806]
   * Replace vol_id command with blkid.
Checksums-Sha1: 
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 f3a29efca7fb860468354593a029c1ef632a9d6c 137898 grml-debootstrap_0.35.tar.gz
 680073b5fb41ca86c412fa898a3f10161904eba9 112724 grml-debootstrap_0.35_all.deb
Checksums-Sha256: 
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 fbfe584d52a91988b92ad8b08dfbd32c33f3b20628908d6fe568a84d08c4b865 137898 grml-debootstrap_0.35.tar.gz
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Files: 
 5cc9b7061f90b763ce4aec1767546210 984 grml optional grml-debootstrap_0.35.dsc
 f4cc660cb48df50c83088285e972bdde 137898 grml optional grml-debootstrap_0.35.tar.gz
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Fixed in git, upload of grml-debootstrap 0.35 should close this issue. Thanks 
for reporting.

what should we do about it? Please comment.

Found the reason, because of 'umount -a':

 $ touch $os_mnt/etc/debootstrap/stages/packages

-- OK.

% chroot $os_mnt
# cat /etc/mtab 
/dev/sda6 / ext3 rw,noatime,nodiratime,barrier=1,errors=remount-ro 0 0
proc /proc proc rw,noexec,nosuid,nodev 0 0
sysfs /sys sysfs rw,noexec,nosuid,nodev 0 0
udev /dev tmpfs rw,mode=0755 0 0
devpts /dev/pts devpts rw,noexec,nosuid,gid=5,mode=620 0 0
none /proc proc rw 0 0
# exit

% chroot $os_mnt umount -a
umount: /dev: not mounted

% touch $os_mnt/etc/debootstrap/stages/packages
touch: cannot touch `/mnt/os11/etc/debootstrap/stages/packages': Read-only file
system

Here is the details:

 $ touch $os_mnt/etc/debootstrap/stages/packages

-- ok

% grml-debootstrap --verbose --confdir=$gdcd --target $os_mnt --nodebootstrap
--packages
 * Using config files under /linux/linux_src/depen/2desk/.
 * grml-debootstrap - Please recheck configuration before execution:

   Target:          /mnt/os11
   Install grub:    no
   Using release:   testing
   Using mirror:    http://debian.mirror.rafal.ca/debian/
   Using hostname:  depen
   Important! Continuing will delete all data from /mnt/os11!

 * Is this ok for you? [y/N] y
 * Not checking Release signatures!
 * Running grml-debootstrap on a directory, skipping mkfs stage.
 * Running grml-debootstrap on a directory, nothing to mount.
 * Skipping debootstrap as requested.
 * Preparing chroot system
`/linux/linux_src/depen/2desk/chroot-script' -> `/mnt/os11/bin/chroot-script'
[. . .]
 * Executing chroot-script now
   [*] Notice: stage chrootmirror has been executed already, skipping execution
therefore.
   [*] Notice: stage grmlrepos has been executed already, skipping execution
therefore.
   [*] Notice: stage kernelimg_conf has been executed already, skipping
execution therefore.
   [*] Notice: stage kernel has been executed already, skipping execution therefore.
   [*] Notice: stage packages has been executed already, skipping execution
therefore.
   [*] Notice: stage extrapackages has been executed already, skipping execution
therefore.
   [*] Notice: stage remove_apt_cache has been executed already, skipping
execution therefore.
   [*] Notice: stage reconfigure has been executed already, skipping execution
therefore.
   [*] Notice: stage hosts has been executed already, skipping execution therefore.
   [*] Notice: stage interfaces has been executed already, skipping execution
therefore.
   [*] Notice: stage timezone has been executed already, skipping execution
therefore.
   [*] Notice: stage fstab has been executed already, skipping execution therefore.
   [*] Notice: stage hostname has been executed already, skipping execution
therefore.
   [*] Notice: stage initrd has been executed already, skipping execution therefore.
   [*] Notice: stage grub_config has been executed already, skipping execution
therefore.
   [*] Notice: stage passwords has been executed already, skipping execution
therefore.
   [*] Notice: stage custom_scripts has been executed already, skipping
execution therefore.
   [*] Notice: stage services has been executed already, skipping execution
therefore.
Finished chroot installation, exiting.                                   [ ok ]
Notice: $GRUB not defined, will not install grub therefore.
 * Removing /var/cache/grml-debootstrap/variables_os11                   [ ok ]
 * Removing /var/cache/grml-debootstrap/stages_os11                      [ ok ]
 * Finished execution of grml-debootstrap. Enjoy your Debian system.     [ ok ]

% touch $os_mnt/etc/debootstrap/stages/packages
touch: cannot touch `/mnt/os11/etc/debootstrap/stages/packages': Read-only file
system

% mount | grep -E $os_mnt 
/dev/sda6 on /mnt/os11 type ext3 (rw)

Forgot to mention, the way I normally use grml-debootstrap:

 grml-debootstrap <optioins> --target <partition_mount_point>

Using the latest grml-debootstrap from git, each time after I use it, the
partition that I work on become read-only. This is less desirable because it
normally takes me several iterations to use grml-debootstrap.