[tracker] Make isBlank() not fail

[Philip Van Hoof <pvanhoof src gnome org>]

commit de08df93af04964d60da52d6f90141d3d12070d1
Author: Philip Van Hoof <philip codeminded be>
Date:   Fri Jul 31 11:03:30 2009 +0200

    Make isBlank() not fail

 src/libtracker-data/tracker-sparql-query.vala |    5 +++++
 1 files changed, 5 insertions(+), 0 deletions(-)
---
diff --git a/src/libtracker-data/tracker-sparql-query.vala b/src/libtracker-data/tracker-sparql-query.vala
index 0636a87..077c68b 100644
--- a/src/libtracker-data/tracker-sparql-query.vala
+++ b/src/libtracker-data/tracker-sparql-query.vala
@@ -1133,6 +1133,11 @@ public class Tracker.SparqlQuery : Object {
 			visit_filter (expr.arg1);
 			pattern_sql.append (")");
 			break;
+		case Rasqal.Op.ISBLANK:
+			/* We don't store blank nodes as blank nodes atm, so we always 
+			 * return false. */
+			pattern_sql.append ("(0)");
+			break;
 		case Rasqal.Op.STR:
 				if (expr.arg1.literal.type == Rasqal.Literal.Type.VARIABLE) {
 					string variable_name = expr.arg1.literal.as_variable ().name;