Document weird bug of Solaris /bin/sh w.r.t. for loops

[Stefano Lattarini]

Hello autoconfers.

Is anyone aware of the following bug of Solaris /bin/sh w.r.t. for 
loops?  I couldn't find any mention of it in the Autoconf manual, and
I think that a proper description of the bug could be an useful 
addition for the manual.

On Solaris 10:
  $ /bin/sh -c 'for a in b=c; do echo "$a"; done'
Unexpectedly, nothing is written on stdout!

Similarly:
 $ /bin/sh -c 'for a in b=c x; do echo "$a"; done'
  x
and again the string "b=c" is not written.

On the other hand:
  $ /usr/xpg4/bin/sh -c 'for a in b=c; do echo "$a"; done'
  b=c
  $ /bin/sh -c 'for a in "b=c"; do echo "$a"; done'
  b=c
  $ /bin/sh -c 'x="b=c"; for a in $x; do echo "$a"; done'
  b=c
  $ /bin/sh -c 'for a in x b=c; do echo "$a"; done'
  x
  b=c

WDYT?

More info about the Solaris system I run the previous tests on:
  SunOS 5.10 Generic_141445-09 i86pc i386 i86pc

Regards,
      Stefano