I have realised that a simpler unexecutable path can be, for example, /etc (is it mandated in POSIX?); this can save the mkstemp() call in the sysdep test.
(And frankly I personally do not really find it much worthwhile to introduce this amount of complexity for the broken dependency of a quite minor performance optimisation...) -- My current OpenPGP key: RSA4096/0x227E8CAAB7AA186C (expires: 2024.09.30) 7077 7781 B859 5166 AE07 0286 227E 8CAA B7AA 186C