bug#22216: test, expr Operator Precedence and Associativity

[積丹尼 Dan Jacobson]

OK. Also make sure (info "(coreutils) test invocation") makes it clear that
one cannot use
test -f $1 -a $1 ! -ot $2 #and must use
test -f $1 -a ! $1 -ot $2 #.