Recommended update for yast2-installation

This update for yast2-installation fixes the following issues:

- Attempts to set read-only property to default BTRFS subvolume failed if the filesystem already existed on disk (boo#1091047)
- Unmounting a filesystem may after installation/upgrade, log a warning (boo#1090018)

Fixed bugs
bnc#1090018
[Build 568.3] Error detected in y2log during upgrade: /mnt: mount point is busy
bnc#1091047
[storage-ng] [Build 588.1] openQA test fails in await_install - cannot umount /dev/vdb1
Selected Binaries
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