webbrowser.open works in IDLE and cmd shell but not from cygwin prompt

[Gregory Bloom]

I'm running Python 2.5 under Windows.  If I fire up IDLE and enter:

>>> import webbrowser
>>> url = 'http://www.python.org'
>>> webbrowser.open_new(url)

it works like a champ, opening the page in Firefox.  Same thing goes
from a Windows cmd shell: it works as advertised.

But if I open a cygwin bash shell and try the same thing from a python
prompt, I get:

>>> import webbrowser
>>> url = 'http://www.python.org'
>>> webbrowser.open_new(url)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "C:\Python25\lib\webbrowser.py", line 60, in open_new
    return open(url, 1)
  File "C:\Python25\lib\webbrowser.py", line 55, in open
    if browser.open(url, new, autoraise):
  File "C:\Python25\lib\webbrowser.py", line 185, in open
    p = subprocess.Popen(cmdline, close_fds=True, preexec_fn=setsid)
  File "C:\Python25\lib\subprocess.py", line 551, in __init__
    raise ValueError("close_fds is not supported on Windows "
ValueError: close_fds is not supported on Windows platforms

What's up with that?  And, more to the point, how can I use webbrowser
from scripts launched under cygwin?