o Minor fix:
    test_util_spawn_background_ok() hardcoded the expected value
    for ENOENT to 2.  This isn't portable as error numbers are
    platform specific, and particularly the hurd has ENOENT at
    0x40000002.  Construct expected string at runtime, using the
    correct value for ENOENT (closes: #4733).  Bugfix on 0.2.3.1-alpha.