Deleting all instructions (i.e. everything from start to end) in a list shows 
the following behaviour:

 The length of the list is not 0 afterwards.
 Only the handle of the first instruction is disposed.

To fix the problem, apply the following patch:

Index: InstructionList.java
===================================================================
--- InstructionList.java	(revision 592025)
+++ InstructionList.java	(working copy)
@@ -677,8 +677,9 @@
     private void remove( InstructionHandle prev, InstructionHandle next )
             throws TargetLostException {
         InstructionHandle first, last; // First and last deleted instruction
-        if ((prev == null) && (next == null)) { // singleton list
-            first = last = start;
+        if ((prev == null) && (next == null)) { 
+            first = start;
+			last = end;
             start = end = null;
         } else {
             if (prev == null) { // At start of list