(release/v20.03) Fix(Dgraph): Type names in exported schema are surro…

…unded by brackets. (#6680)

If they are not surrounded by brackets, type names with special
characters will not be able to be imported to a new DB.

Fixes DGRAPH-2462.

(cherry picked from commit 51821f3)

worker/export.go

@@ -318,7 +318,7 @@ func toSchema(attr string, update *pb.SchemaUpdate) (*bpb.KVList, error) {
 
 func toType(attr string, update pb.TypeUpdate) (*bpb.KVList, error) {
 	var buf bytes.Buffer
-	x.Check2(buf.WriteString(fmt.Sprintf("type %s {\n", attr)))
+	x.Check2(buf.WriteString(fmt.Sprintf("type <%s> {\n", attr)))
 	for _, field := range update.Fields {
 		x.Check2(buf.WriteString(fieldToString(field)))
 	}