TEST-58: only run under qemu

In a container, /dev/loop* will most likely be inaccessible.

test/TEST-58-REPART/test.sh

@@ -1,6 +1,7 @@
 #!/usr/bin/env bash
 set -e
 TEST_DESCRIPTION="test systemd-repart"
+TEST_NO_NSPAWN=1
 . $TEST_BASE_DIR/test-functions
 
 do_test "$@" 58