ci: Remove redundant busybox option

The option was fine, but now that there is a dedicated Alpine Linux
task, which uses BusyBox, it seems redundant.
(See: ci/test/00_setup_env_native_alpine_musl.sh)

So remove the USE_BUSY_BOX option, along with the BINS_SCRATCH_DIR env
var.

Also, enable pipefail in the ci/test/00_setup_env.sh script, while
touching it.

ci/test/00_setup_env.sh

@@ -6,7 +6,7 @@
 
 export LC_ALL=C.UTF-8
 
-set -ex
+set -o errexit -o pipefail -o xtrace
 
 # The source root dir, usually from git, usually read-only.
 # The ci system copies this folder.
@@ -22,9 +22,6 @@ export DEPENDS_DIR=${DEPENDS_DIR:-$BASE_ROOT_DIR/depends}
 # A folder for the ci system to put temporary files (build result, datadirs for tests, ...)
 # This folder only exists on the ci guest.
 export BASE_SCRATCH_DIR=${BASE_SCRATCH_DIR:-$BASE_ROOT_DIR/ci/scratch}
-# A folder for the ci system to put executables.
-# This folder only exists on the ci guest.
-export BINS_SCRATCH_DIR="${BASE_SCRATCH_DIR}/bins/"
 
 echo "Setting specific values in env"
 if [ -n "${FILE_ENV}" ]; then
@@ -36,8 +33,6 @@ fi
 echo "Fallback to default values in env (if not yet set)"
 # The number of parallel jobs to pass down to make and test_runner.py
 export MAKEJOBS=${MAKEJOBS:--j$(if command -v nproc > /dev/null 2>&1; then nproc; else sysctl -n hw.logicalcpu; fi)}
-# Whether to prefer BusyBox over GNU utilities
-export USE_BUSY_BOX=${USE_BUSY_BOX:-false}
 
 export RUN_UNIT_TESTS=${RUN_UNIT_TESTS:-true}
 export RUN_FUNCTIONAL_TESTS=${RUN_FUNCTIONAL_TESTS:-true}

ci/test/00_setup_env_arm.sh

@@ -8,11 +8,10 @@ export LC_ALL=C.UTF-8
 
 export HOST=arm-linux-gnueabihf
 export DPKG_ADD_ARCH="armhf"
-export PACKAGES="python3-zmq g++-arm-linux-gnueabihf busybox libc6:armhf libstdc++6:armhf libfontconfig1:armhf libxcb1:armhf"
+export PACKAGES="python3-zmq g++-arm-linux-gnueabihf libc6:armhf libstdc++6:armhf libfontconfig1:armhf libxcb1:armhf"
 export CONTAINER_NAME=ci_arm_linux
 export CI_IMAGE_NAME_TAG="mirror.gcr.io/ubuntu:24.04"  # Check that https://packages.ubuntu.com/noble/g++-arm-linux-gnueabihf (version 13.x, similar to guix) can cross-compile
 export CI_IMAGE_PLATFORM="linux/arm64"
-export USE_BUSY_BOX=true
 export RUN_UNIT_TESTS=true
 export RUN_FUNCTIONAL_TESTS=false
 export GOAL="install"

ci/test/02_run_container.sh

@@ -18,16 +18,13 @@ else
 fi
 
 CI_EXEC () {
-  $CI_EXEC_CMD_PREFIX bash -c "export PATH=\"/path_with space:${BINS_SCRATCH_DIR}:${BASE_ROOT_DIR}/ci/retry:\$PATH\" && cd \"${BASE_ROOT_DIR}\" && $*"
+  $CI_EXEC_CMD_PREFIX bash -c "export PATH=\"/path_with space:${BASE_ROOT_DIR}/ci/retry:\$PATH\" && cd \"${BASE_ROOT_DIR}\" && $*"
 }
 export -f CI_EXEC
 
 # Normalize all folders to BASE_ROOT_DIR
 CI_EXEC rsync --recursive --perms --stats --human-readable "${BASE_READ_ONLY_DIR}/" "${BASE_ROOT_DIR}" || echo "Nothing to copy from ${BASE_READ_ONLY_DIR}/"
 CI_EXEC "${BASE_ROOT_DIR}/ci/test/01_base_install.sh"
-
-CI_EXEC mkdir -p "${BINS_SCRATCH_DIR}"
-
 CI_EXEC "${BASE_ROOT_DIR}/ci/test/03_test_script.sh"
 
 if [ -z "$DANGER_RUN_CI_ON_HOST" ]; then

ci/test/03_test_script.sh

@@ -85,15 +85,6 @@ elif [ "$RUN_UNIT_TESTS" = "true" ]; then
   fi
 fi
 
-if [ "$USE_BUSY_BOX" = "true" ]; then
-  echo "Setup to use BusyBox utils"
-  # tar excluded for now because it requires passing in the exact archive type in ./depends (fixed in later BusyBox version)
-  # ar excluded for now because it does not recognize the -q option in ./depends (unknown if fixed)
-  for util in $(busybox --list | grep -v "^ar$" | grep -v "^tar$" ); do ln -s "$(command -v busybox)" "${BINS_SCRATCH_DIR}/$util"; done
-  # Print BusyBox version
-  patch --help
-fi
-
 # Make sure default datadir does not exist and is never read by creating a dummy file
 if [ "$CI_OS_NAME" == "macos" ]; then
   echo > "${HOME}/Library/Application Support/Bitcoin"