remove --overwrite option

install_spack_env.sh

@@ -56,7 +56,7 @@ spack env activate $EBRAINS_SPACK_ENV
 # remove the .lock file and let the enironment be concretized by the spack install command:
 rm $SPACK_ROOT/var/spack/environments/$EBRAINS_SPACK_ENV/spack.lock || echo "No spack.lock file"
 # install the environment, use 2 jobs to reduce the amount of required RAM
-spack install --overwrite -y -j2 --fresh --test root
+spack install -y -j2 --fresh --test root
 
 # rebuild spack's database
 spack reindex