I catched Roland Mainz on IRC and he told me that this is a bug with
Solaris 11.1+ ksh93:
23:37 < nrubsig> technically it was fixed for the ksh93 version
shipped with OpenSolaris integrated in OS/Net... but
then Sun pulled out out of OS/Net and forgot to add
the XPG6 build flags which fix this mess... so it is
fixed in Solaris 11 and broken for the updateds of
Solaris 11 and Solaris 11.1
...
23:38 < nrubsig> technically its an issue with build flags, e.g. make
sure the XPG6 personality in libc is enabled.