Update go-dockerlibrary to include https://github.com/docker-library/go-dockerlibrary/pull/19

bashbrew/go/vendor/manifest

@@ -10,7 +10,7 @@
 		{
 			"importpath": "github.com/docker-library/go-dockerlibrary",
 			"repository": "https://github.com/docker-library/go-dockerlibrary",
-			"revision": "dd7d405dfece72f87c382d7c0495ad44235f9ebb",
+			"revision": "78186ac78fb8c1ce4e0f2f4847ae4d57a69cfcc3",
 			"branch": "master"
 		},
 		{

bashbrew/go/vendor/src/github.com/docker-library/go-dockerlibrary/manifest/line-based.go

@@ -80,5 +80,12 @@ func ParseLineBased(readerIn io.Reader) (*Manifest2822, error) {
 		}
 	}
 
+	if len(manifest.Global.Maintainers) < 1 {
+		return nil, fmt.Errorf("missing Maintainers")
+	}
+	if invalidMaintainers := manifest.Global.InvalidMaintainers(); len(invalidMaintainers) > 0 {
+		return nil, fmt.Errorf("invalid Maintainers: %q (expected format %q)", strings.Join(invalidMaintainers, ", "), MaintainersFormat)
+	}
+
 	return manifest, nil
 }