Wubi fails without explanation on restrictive networks

[Duncan Lithgow]

Wubi (rev 211 for 11.04 64bit)
Windows 7

Wubi can't fetch install data on a restrictive network with bittorrent ports closed. That would include many corporate networks. Wubi fails as described in bug #156922. One reason why this silent failure is such a problem is that the log file is in the c:\users\username\appdata\ - but appdata is hidden by default in Windows 7, effectively preventing many wubi users from ever finding the log file, and us hearing about the problem.

Off the top of my head wubi could deal with this as follows:

* Wubi should check for a working torrent connection before bothering to collect user data
* If the connection test fails Wubi should explain the problem
* Wubi should offer alternative ways to fetch the iso
  (now the user has fetched the iso manually)
* When failing the network test (on being re-run) it should offer the user the chance to point to the iso manually