bug (and its fix (depending upon whether the test is run against
an unfixed, or fixed, shell).
An obvious indication of the failure is the following (one of the
new sub-tests)
p=A
cat <<EOF
${p+\%$p\%}
${p+%$p%}
EOF
which should output
\%A\%
%A%
as a here doc is treated as a double quoted string, except
that the " character is just a character. In such a string,
the \ is only an escape character when the following character
is special, otherwise it represents a literal \ (which is the
case here).
An unfixed shell will omit the backslashes in the output.
It gets even more wrong if the % chars are replaced by "
(double quote) chars, which should make no difference, other
than the corresponding change, in the output. But doesn't
(it doesn't even produce output broken in a similar way).
This one is a harder case to be specific about however,
as while the fixed (and expected in the test) output is what
is technically correct, only a few shells actually produce
it, most generate something different (but not all the same.)