Taylor Blau [off-list ref] writes:

Given this and the above, I would probably err on the side of
designating this as 'test_lazy_prereq' or otherwise silencing the output
of 'test_cmp' so that this does not taint the TAP output.

We can argue the merit and demerit with a good log message.  The
central issue at hand is how precious 52a9 in the script lost by
this patch is (in other words, are we checking more than "is our
char signed or unsigned?").

By the way, I do not quite get the _BY_DEFAULT in the name
SIGNED_CHAR_BY_DEFAULT.  The builder may have configured to use
signed char on a platform that can handle both and their char is by
default unsigned, and under such a condition, we would set this
prerequisite, even though the default on such a platform is
unsigned, no?