--- FAIL: TestBtrfs (0.00s)
    --- FAIL: TestBtrfs/RemoveDirectoryInLowerLayer (0.14s)
        testsuite.go:96: Failed to initialize snapshotter: skip plugin
            github.com/containerd/containerd/plugin.init.ializers
            	/home/travis/gopath/src/github.com/containerd/containerd/plugin/plugin.go:38
            runtime.main
            	/home/travis/.gimme/versions/go1.12.9.linux.amd64/src/runtime/proc.go:188
            runtime.goexit
            	/home/travis/.gimme/versions/go1.12.9.linux.amd64/src/runtime/asm_amd64.s:1337
            path /tmp/snapshot-suite-Btrfs-805133001/root must be a btrfs filesystem to be used with the btrfs snapshotter
            github.com/containerd/containerd/snapshots/btrfs.NewSnapshotter
            	/home/travis/gopath/src/github.com/containerd/containerd/snapshots/btrfs/btrfs.go:80
            github.com/containerd/containerd/snapshots/btrfs.boltSnapshotter.func1
            	/home/travis/gopath/src/github.com/containerd/containerd/snapshots/btrfs/btrfs_test.go:70
            github.com/containerd/containerd/snapshots/testsuite.makeTest.func1
            	/home/travis/gopath/src/github.com/containerd/containerd/snapshots/testsuite/testsuite.go:94
            testing.tRunner
            	/home/travis/.gimme/versions/go1.12.9.linux.amd64/src/testing/testing.go:865
            runtime.goexit
            	/home/travis/.gimme/versions/go1.12.9.linux.amd64/src/runtime/asm_amd64.s:1337
            failed to create new snapshotter
            github.com/containerd/containerd/snapshots/btrfs.boltSnapshotter.func1
            	/home/travis/gopath/src/github.com/containerd/containerd/snapshots/btrfs/btrfs_test.go:73
            github.com/containerd/containerd/snapshots/testsuite.makeTest.func1
            	/home/travis/gopath/src/github.com/containerd/containerd/snapshots/testsuite/testsuite.go:94
            testing.tRunner
            	/home/travis/.gimme/versions/go1.12.9.linux.amd64/src/testing/testing.go:865
            runtime.goexit
            	/home/travis/.gimme/versions/go1.12.9.linux.amd64/src/runtime/asm_amd64.s:1337