Is this a possible bug in SunOS setpgrp() ?

[john.urban]

In article <1991May21.022214.1189 at sserve.cc.adfa.oz.au> wkt at csadfa.cs.adfa.oz.au (Warren Toomey) writes:
>I include a short program which appears to demonstrate a bug in the
>setpgrp() under SunOS 4.1.1. The program works under Pyramid OSx, and
>I think should work under previous version of SunOS. If anybody can show
>me that the bug is in fact a programming error I'd be most happy!
>
>Thanks in advance,

When fred is compiled on AT&T UNIX System V/x86 Release 4.0 Version 2.1, I get:

$ ./fred
Forked, now we pause()
Writing to stdout
$

If I then change fred and uncomment the 'bug' line I get:
$ ./fred
Forked, now we pause()
Can I write??
Writing to stdout
$

Sincerely,

John Ben Urban