ksh93 oddity

gistfile1.sh

Why does ksh93 behave differently to every other bourne-derived shell (and ksh88)?

Turning braceexpand off makes no difference.

# Solaris 9 bourne shell
$ sh -c 'set -- "foo={one,two}"; echo $1'
foo={one,two}

# dash from Ubuntu
$ dash -c 'set -- "foo={one,two}"; echo $1'
foo={one,two}

# bash 3.2.48(1)-release
$ bash -c 'set -- "foo={one,two}"; echo $1'
foo={one,two}

# zsh 4.3.11
$ zsh -c 'set -- "foo={one,two}"; echo $1'
foo={one,two}

# PD KSH v5.2.14
$ ksh -c 'set -- "foo={one,two}"; echo $1'
foo={one,two}

# Solaris 9 /bin/ksh (M-11/16/88i)
$ ksh -c 'set -- "foo={one,two}"; echo $1'
foo={one,two}

# ksh 1993-12-28 s+
$ ksh -c 'set -- "foo={one,two}"; echo $1'
foo=one foo=two

# ksh 93t+ 2010-03-05
$ ksh -c 'set -- "foo={one,two}"; echo $1'
foo=one foo=two