[MASTER] ubiquity should warn users about unusable mounted partitions

[Evan]

Binary package hint: ubiquity

From #ubuntu-installer:
<evand> cjwatson: do you recall why we decided to filter all disks with mounted partitions from parted_devices rather than just /cdrom?
 It seems to be creating a headache for a number of users, and I'm wondering if we should try to unmount the partitions in question, then try again, or filter less out.
<cjwatson> evand: because if any partition is mounted on a disk then you can't tell the kernel to reread its partition table. We added partman/filter_mounted so that they can control it
<evand> oh, of course
<cjwatson> I think this is a bit of a lose-lose situation
<evand> Ugly, but perhaps a dialog warning them that they wont see the following disks because they have mounted partitions
<cjwatson> or a question asking them whether they want to unmount those partitions or not; of course they may have documents open on them ...
 feels like perhaps the sort of thing that should be done in ubiquity rather than partman-base
 in d-i it's much less likely that partitions will be mounted
<evand> indeed
<cjwatson> no objection to ameliorating the lose-lose on either side of course :-)

Following this, we should move the partition filtering into ubiquity and wrap it in a debconf question that asks if the user wants the installer to try and unmount the partitions that will be filtered out before continuing.

[Andreas Kern (kerna)]

this seems to be a duplicate of Bug #290415

[Evan (ev)]

I think we still need to do this in partman-base, as we don't want the disk we're installing from to appear when usb-creator was used to create an alternate image.

[Evan (ev)]

Proposed patch

[Evan (ev)]

Fixed in the latest daily-live CD:
http://cdimage.ubuntu.com/daily-live/20090317/jaunty-desktop-i386.iso