[p4] problem with programming perforce via python

[Roger Day]

I'm trying to do the following

log = logging.getLogger("hope2p4")
cmd =self.p4+' change -i -o'
p = Popen(cmd, stdout=PIPE, stdin=PIPE, close_fds=True, bufsize=1, 
shell=True)
lcmd = 'Change: new\n'
(author, reason, bugnr)=metadata
lcmd += 'Description:\n\t['+ bugnr+'] '+reason+'\n'
lcmd += 'Files: \n\t'+f+'\n\n'
log.info("lcmd: "+lcmd)
p.stdin.write( lcmd )
p.stdin.close()
out =p.stdout.read()
(pre, nr, end)=out.split(' ')
return nr

A changelist number is returned, but the changelist doesn't contain any 
files.

Once I've created the change-list I then go on to submit in a similar 
fashion but can't because the changelist contains no files.

Any help gratefully received.

Roger