If bash is invoked with the name sh, it tries to mimic the
startup behavior of historical versions of sh as closely
as possible, while conforming to the POSIX standard as
well.
So, if POSIX says that the example above should be
$ echo hello {there,world}
hello {there,world}
then this is a bug in bash, IMHO. Can somebody check bash for other
non-POSIX features is has when called as `sh' and file bug reports for
them?
`startup behavior' is not the same as `behavior while bash is
running.' `startup behavior' just means what dotfiles get run at bash
startup time.
