Do not use qcow2 images by default

README.md

@@ -37,7 +37,7 @@ The following environment variables are supported:
    but you should use something else for a customized version.  Export files
    in stages may add suffixes to `IMG_NAME`.
 
-* `USE_QCOW2`(Default: `1` )
+* `USE_QCOW2` **EXPERIMENTAL** (Default: `0` )
 
     Instead of using traditional way of building the rootfs of every stage in
     single subdirectories and copying over the previous one to the next one,

build.sh

@@ -253,7 +253,7 @@ source "${SCRIPT_DIR}/common"
 source "${SCRIPT_DIR}/dependencies_check"
 
 export NO_PRERUN_QCOW2="${NO_PRERUN_QCOW2:-1}"
-export USE_QCOW2="${USE_QCOW2:-1}"
+export USE_QCOW2="${USE_QCOW2:-0}"
 export BASE_QCOW2_SIZE=${BASE_QCOW2_SIZE:-12G}
 source "${SCRIPT_DIR}/qcow2_handling"
 if [ "${USE_QCOW2}" = "1" ]; then