test: Fix unshare/nsenter not in PATH

Signed-off-by: Jacques de Laval <jacques@de-laval.se>

test/testenv_exec.sh

@@ -13,8 +13,10 @@ shift
 TEST_DIR=$(dirname "$0")
 TESTS_ROOT="$(pwd)/${TEST_DIR}/test_root"
 
+nsenter=$(which nsenter)
+
 export PATH=/sbin:/bin
-nsenter \
+"$nsenter" \
     --preserve-credentials \
     --user \
     --mount \

test/testenv_start.sh

@@ -7,10 +7,12 @@ TESTS_ROOT="$(pwd)/${TEST_DIR}/test_root"
 
 >&2 echo "Hint: Execute '${TEST_DIR}/testenv_exec.sh \$(pgrep -P $$) /bin/sh; reset' to enter the test namespace"
 
+unshare=$(which unshare)
+
 # Not supported by Busybox unshare:
 #  --cgroup --time
 export PATH=/sbin:/bin
-exec unshare \
+exec "$unshare" \
     --user --map-root-user \
     --fork --pid --mount-proc \
     --mount \