os-prober 1.51ubuntu3 (Precise) does not recognize windows recovery partition while os-prober 1.38 (Lucid) do

Hello I just installed Ubuntu 12.04 on my laptop over my old Ubuntu 10.04.
I also have dual boot with Windows XP media Center Edition (after the new installation it's still booting fine).
In my previous Ubuntu Installation (10.04 Lucid Lynx), i had two line in GRUB for the windows partitions :
-one for the recovery partition (on sda1)
-one for the windows MCE partition (on sda2).

In my new Ubuntu installation (Precise Pangoling 12.04), I just get one line for windows MCE partition (sda2) (which i still booting fine no problem on that side) and the line for the recovery partition is gone (i don't use it often but I just have to boot on it if i want to restore the windows partition to factory state, that's very handy). Now I'm unable to do that because the partition does not show up anymore.

After some research it turned out that os-prober (1.51ubuntu3 from Ubuntu 12.04) does not recognize the partition on sda1 as a windows partition. Here a the details :
lsb_release -rd gives
Ubuntu version : (-> that's the one installed on my laptop (sda6)
Description: Ubuntu 12.04 LTS
Release: 12.04

apt-cache policy os-prober
os-prober:
  Installé : 1.51ubuntu3
  Candidat : 1.51ubuntu3
 Table de version :
 *** 1.51ubuntu3 0
        500 http://de.archive.ubuntu.com/ubuntu/ precise/main i386 Packages
        100 /var/lib/dpkg/status

Here is the os-prober output :
/dev/sda2:Windows XP Media Center Edition:Windows:chain

I also use a Ubuntu 10.04 on a live CD the check the behaviour of my former installation :
lsb_release -rd ( -> live-CD)
Description: Ubuntu 10.04.4 LTS
Release: 10.04

apt-cache policy os-prober
os-prober:
  Installé : 1.38
  Candidat : 1.38
 Table de version :
 *** 1.38 0
        500 http://archive.ubuntu.com/ubuntu/ lucid/main Packages
        100 /var/lib/dpkg/status

Here is the os-prober output using os-prober 1.38 on the live CD of Ubuntu 10.04
/dev/sda1:Windows NT/2000/XP:Windows:chain (-> recovery partition, not found by os-prober 1.51ubuntu3)
/dev/sda2:Windows XP Media Center Edition:Windows1:chain (-> win XP partition , found by both)
/dev/sda6:Ubuntu 12.04 LTS (12.04):Ubuntu:linux (-> the Ubuntu 12.04 installed on my laptop)

I also checked the changelog of os-prober the launchpad website but didn't read anything that could explain my problem.
I alsa compared the 20microsoft files of os-prober for both version (found in /usr/lib/os-probes/mounted/) but didn't see any evident solutions (i'm no expert).

Finally, some websites advised to use bootinfoscript to look what's happening on the drive. Here is the result of the script (sorry I don't see any button for attaching a file, so I just give you the interesting part)
                  Boot Info Script 0.61 [1 April 2012]

============================= Boot Info Summary: ===============================

 => Grub2 (v1.99) is installed in the MBR of /dev/sda and looks at sector 1 of
    the same hard drive for core.img. core.img is at this location and looks
    for (,msdos6)/boot/grub on this drive.

sda1: __________________________________________________________________________

    File system: vfat
    Boot sector type: Windows XP: FAT32
    Boot sector info: No errors found in the Boot Parameter Block.
    Operating System:
    Boot files: /ntldr /NTDETECT.COM

sda2: __________________________________________________________________________

    File system: ntfs
    Boot sector type: Windows XP: NTFS
    Boot sector info: No errors found in the Boot Parameter Block.
    Operating System: Windows XP
    Boot files: /boot.ini /ntldr /NTDETECT.COM

sda3: __________________________________________________________________________

    File system: ntfs
    Boot sector type: Windows Vista/7: NTFS
    Boot sector info: No errors found in the Boot Parameter Block.
    Operating System:
    Boot files:

sda4: __________________________________________________________________________

    File system: Extended Partition
    Boot sector type: Unknown
    Boot sector info:

sda5: __________________________________________________________________________

    File system: swap
    Boot sector type: -
    Boot sector info:

sda6: __________________________________________________________________________

    File system: ext4
    Boot sector type: -
    Boot sector info:
    Operating System: Ubuntu 12.04 LTS
    Boot files: /boot/grub/grub.cfg /etc/fstab /boot/grub/core.img

============================ Drive/Partition Info: =============================

Drive: sda _____________________________________________________________________

Disk /dev/sda: 120.0 GB, 120034123776 bytes
255 têtes, 63 secteurs/piste, 14593 cylindres, total 234441648 secteurs
Unités = secteurs de 1 * 512 = 512 octets
Taille de secteur (logique / physique) : 512 octets / 512 octets

Partition Boot Start Sector End Sector # of Sectors Id System

/dev/sda1 * 63 8,193,149 8,193,087 b W95 FAT32
/dev/sda2 8,193,150 110,591,459 102,398,310 7 NTFS / exFAT / HPFS
/dev/sda3 110,591,460 161,790,614 51,199,155 7 NTFS / exFAT / HPFS
/dev/sda4 161,790,676 234,436,544 72,645,869 5 Extended
/dev/sda5 161,790,678 163,830,869 2,040,192 82 Linux swap / Solaris
/dev/sda6 163,830,933 234,436,544 70,605,612 83 Linux

"blkid" output: ________________________________________________________________

Device UUID TYPE LABEL

/dev/sda1 4481-6862 vfat RECOVERY
/dev/sda2 5E508F63508F412F ntfs WINDOWS
/dev/sda3 1B2933F96200AE43 ntfs DATA
/dev/sda5 7dbac558-cfa0-4cf8-8036-a22d2702d693 swap
/dev/sda6 9df8b567-f220-4bb4-aeb0-e3f8d56ad5ca ext4

I'm not sure if it is a bug, so I filed a question. I'd like to get the recovery partion recognized by os-prober again (as in os-prober 1.38). Yet I can't tell between which two consecutive versions of os-prober the problem did appear.

If there is way to install old version of os-prober in Ubuntu 12.04 (i don't know ), I could figure out when the problem did appear.

I tried to be as detailed as possible. All my installation are 32bit (if that make a difference).

Thank you for your help. Contact me for any additional information I may have forgotten.