Hack the Windows code to use os.popen().
The returned file is assigned to an instance variable;
otherwise the implied close hangs for a long time.
diff --git a/Lib/webbrowser.py b/Lib/webbrowser.py
index 5a4a80f..66cdbff 100644
--- a/Lib/webbrowser.py
+++ b/Lib/webbrowser.py
@@ -183,9 +183,7 @@
 
 class WindowsDefault:
     def open(self, url, new=0):
-        import win32api, win32con
-        win32api.ShellExecute(0, "open", url, None, ".",
-                              win32con.SW_SHOWNORMAL)
+        self.junk = os.popen("start " + url)
 
     def open_new(self, url):
         self.open(url)