Documentation and docstrings for the 'cmd'-as-sequence
usage of popenX functions in os and popen2 on unix. 
All texts are a variation on the following:
    On \UNIX, \var{cmd} may be a sequence, in which
case arguments will be passed directly to the program
without shell intervention (as with
\function{os.spawnv()}.  If \var{cmd} is a string it
will be passed to the shell (as with
\function{os.system()}).

See also 888380 for an older patch addressing the same
issue.  If this patch is applied, that tracker item
should be closed too.

Logged In: YES 
user_id=469548

Checking in Doc/lib/libos.tex;
/cvsroot/python/python/dist/src/Doc/lib/libos.tex,v  <-- 
libos.tex
new revision: 1.143; previous revision: 1.142
done
Checking in Doc/lib/libpopen2.tex;
/cvsroot/python/python/dist/src/Doc/lib/libpopen2.tex,v  <--
 libpopen2.tex
new revision: 1.23; previous revision: 1.22
done
Checking in Lib/os.py;
/cvsroot/python/python/dist/src/Lib/os.py,v  <--  os.py
new revision: 1.83; previous revision: 1.82
/cvsroot/python/python/dist/src/Doc/lib
done
Checking in Lib/popen2.py;
/cvsroot/python/python/dist/src/Lib/popen2.py,v  <--  popen2.py
new revision: 1.30; previous revision: 1.29
done

I made a couple of changes before checking in:

* In libos.tex, I moved the text out of the popen4 function
description, and into the block above the popen2/3/4
definitions.
* In libpopen.text, I moved the text up a bit.
* In popen2.py, I added the text to the functions in the
other block of platforms as well.