Architecture empty on systems without dpkg

If using grml-debootstrap on non-Debian-based systems should be supported, then without dpkg being installed, the variable ARCH should be checked to be not-empty, so debootstrap is not called with --arch with no actual architecture.

 * Running debootstrap  for release bullseye () using http://deb.debian.org/debian
 * Executing: debootstrap --arch    bullseye /mnt/debootstrap.60629 http://deb.debian.org/debian
/usr/sbin/debootstrap: line 505: cd: http://deb.debian.org: No such file or directory
 -> Failed (rc=1)
 * Removing /var/cache/grml-debootstrap/stages_qemu-test-grml.img

The code:

grml-debootstrap/grml-debootstrap

Lines 1149 to 1158 in 4d625ea

    
           # architecture setup {{{ 
        
           if [ -n "$ARCH" ] ; then 
        
              ARCHCMD="--arch $ARCH" 
        
              ARCHINFO=" (${ARCH})" 
        
           else 
        
              ARCH="$(dpkg --print-architecture)" 
        
              ARCHCMD="--arch $ARCH" 
        
              ARCHINFO=" (${ARCH})" 
        
           fi 
        
           # }}}

Specifying the architecture explicitly, for example --arch amd64, fixes the problem.

	# architecture setup {{{
	if [ -n "$ARCH" ] ; then
	ARCHCMD="--arch $ARCH"
	ARCHINFO=" (${ARCH})"
	else
	ARCH="$(dpkg --print-architecture)"
	ARCHCMD="--arch $ARCH"
	ARCHINFO=" (${ARCH})"
	fi
	# }}}