Avoid running oem-config in recovery mode.

Applied with some small adjustments, thanks.

This bug was fixed in the package ubiquity - 2.5.28

---------------
ubiquity (2.5.28) natty; urgency=low

  [ Evan Dandrea ]
  * Update the descriptions for the automatic partitioning options to match
    changes to the specification (LP: #736959).
  * Mount /proc and friends for apt-clone.
  * Use the noninteractive debconf frontend when calling apt-clone.
  * apt-clone is now a separate package.
  * Add a partitioning heading to help clarify what operating systems
    may be acted upon by the installer.
  * Remove ' (loader)' from the os-prober operating system descriptions on
    the initial partitioning page.
  * Properly substitute in the non-Ubuntu system when generating descriptions
    for dual boot partitioning.
  * Remove alpha warning for reuse option in preparation for the 11.04 Beta.
  * Update translations from Launchpad.
  * Automatic update of included source packages: console-setup
    1.57ubuntu17, grub-installer 1.60ubuntu2, localechooser 2.34ubuntu3,
    partman-auto 93ubuntu13, partman-auto-loop 0ubuntu19.

  [ Colin Watson ]
  * Preprocess our variant of keyboard-configuration.postinst, so that it
    includes the keyboard_present function.
  * Start oem-config-debconf on stopping rc RUNLEVEL=[2345], rather than on
    (filesystem and stopped udevtrigger); this guarantees that we will never
    end up without a controlling terminal because tty1 has already started.
  * Don't run the oem-config job in recovery mode (thanks, Shih-Yuan Lee;
    LP: #734695).
  * Run plugininstall in debconf frontend (LP: #740183).
 -- Evan Dandrea <email address hidden> Wed, 23 Mar 2011 20:22:00 +0000