[Merge] lp:~mitya57/metacity/3.12.0 into lp:~ubuntu-desktop/metacity/ubuntu

[Colin Watson]

As mentioned on IRC, ubiquity was already enabling metacity's compositing manager, so I see no reason to fear that this will break ubiquity if it otherwise works as a window manager.
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https://code.launchpad.net/~mitya57/metacity/3.12.0/+merge/226573
Your team Ubuntu Development Team is requested to review the proposed merge of lp:~mitya57/metacity/3.12.0 into lp:~ubuntu-desktop/metacity/ubuntu.