POSIX requires accepting unquoted newlines in word in parameter expansions
like ${param+word}, ${param#word}, although the Bourne shell did not support
it, it is not commonly used and might make it harder to find a missing
closing brace.
It was also strange that something like
foo="${bar#
}"
was rejected.
Reported by: Martijn Dekker via Robert Elz
29988d0ef0