MessageCommons had to be fixed in rSHWK4094 and rSHWK4095 so that it doesn't break when Gadgets is installed at the same time, both used to be installed at the same time at some point in the past but something in MW core changed in a way which changed MessageCommons' behavior, which somehow ended up breaking Gadgets.
We should research and see if we can redeploy Gadgets on ShoutWiki globally :-)