fai-mirror has problems with variables

[Holger Schurig]

# export kernelversion=2.6.10
# export kernelsubversion=1-686
# fai-mirror -cDEFAULT -v .
Getting package information
Downloading packages for classes: DEFAULT
Reading config file /etc/fai/install_packages.conf
install_packages: read config 
file /usr/local/share/fai/package_config/DEFAULT
install_packages: executing  apt-get -qq -d         -o 
Aptitude::Log=/dev/null       -o Dir::State::status=./aptcache/statefile       
-o Dir::Cache=./aptcache/var/cache/apt       -o 
Dir::State=./aptcache/var/cache/apt       -o 
Dir::Cache::Archives=./aptcache/var/cache/apt/archives       -o 
Dir::Etc::sourcelist=./aptcache/etc/apt/sources.list       -o 
Dir::State::Lists=./aptcache/var/lib/apt/lists/ -y --force-yes 
--fix-missing install file hdparm less module-init-tools
install_packages: executing  true
install_packages: executing  true
install_packages: executing  true
install_packages: executing  true
Adding packages from variable $addpackages: 
kernel-image-${kernelversion}-${kernelsubversion}E: Regex compilation 
error - Invalid preceding regular expression
 kernel-image-${kernelversion}-${kernelsubversion}E: Regex compilation 
error - Invalid preceding regular expression
 kernel-image-${kernelversion}-${kernelsubversion}E: Regex compilation 
error - Invalid preceding regular expression
...