Adding a spare to an existing MD array, causes an error

[Sami Haahtinen]

After selecting "add spare" in an degraded software RAID1 array and selecting an empty space to use I get the following error:

Error adding component to RAID Array

An error occurred while performing an operation on "raidarrayname" (1,5 TB RAID-1 Array): The operation failed
Error adding spare: mdadm exited with exit code 2: mdadm:option --force not valid in manage mode

Manually running mdadm on the newly created partition works with no problems.

ProblemType: Bug
DistroRelease: Ubuntu 12.04
Package: gnome-disk-utility 3.0.2-2ubuntu6
ProcVersionSignature: Ubuntu 3.2.0-12.21-generic 3.2.2
Uname: Linux 3.2.0-12-generic x86_64
NonfreeKernelModules: fglrx
ApportVersion: 1.91-0ubuntu1
Architecture: amd64
Date: Fri Feb 3 12:17:49 2012
ExecutablePath: /usr/bin/palimpsest
SourcePackage: gnome-disk-utility
UpgradeStatus: Upgraded to precise on 2011-12-27 (38 days ago)