feature #3782: Deal with snapshot id=0

include/Snapshots.h

@@ -131,7 +131,7 @@ private:
     /**
      * Id of the active (current) snapshot, 0 represents the base image
      */
-    unsigned int active;
+    int active;
 
     /**
      * Id of the disk associated with this snapshot list

src/vm/Snapshots.cc

@@ -145,19 +145,16 @@ int Snapshots::active_snapshot(unsigned int id, string& error)
         return 0;
     }
 
-    if ( id != 0 )
+    snapshot = get_snapshot(id);
+
+    if (snapshot == 0)
     {
-        snapshot = get_snapshot(id);
-
-        if (snapshot == 0)
-        {
-            error = "Snapshot does not exists";
-            return -1;
-        }
-
-        snapshot->replace("ACTIVE", true);
+        error = "Snapshot does not exists";
+        return -1;
     }
 
+    snapshot->replace("ACTIVE", true);
+
     snapshot = get_snapshot(active);
 
     if (snapshot != 0)