Comment 19 for bug 1481536

I'm attaching another revision of the patch (v3).

Changes from v2:

  * skip calls to udev_settle() if the device of interest already
    exists
  * don't assume the unlocked device will appear after udev_settle()
    (sleep until the device appears, if necessary)
  * wait for the LVM logical volume device to appear before getting
    the filesystem type
  * remove an unnecessary call to udev_settle()
  * clean up the password retry loop (move out logic that doesn't
    belong there, move in logic that does, simplify some logic)
  * delete commented-out code

You can see the above changes individually and with (somewhat)
descriptive commit messages in my GitHub repo:
https://github.com/rhansen/ubuntu-bug1481536-cryptroot

The patched package has been uploaded to my PPA:
https://launchpad.net/~rhansen/+archive/ubuntu/bug1481536