Index: generic/tclExecute.c
===================================================================
RCS file: /cvsroot/tcl/tcl/generic/tclExecute.c,v
retrieving revision 1.369.2.14
diff -u -r1.369.2.14 tclExecute.c
--- generic/tclExecute.c	2 Jul 2010 20:58:07 -0000	1.369.2.14
+++ generic/tclExecute.c	1 Sep 2010 15:01:30 -0000
@@ -2885,14 +2885,14 @@
 	valuePtr = OBJ_AT_TOS; /* value to append */
 	part2Ptr = NULL;
 	storeFlags = (TCL_LEAVE_ERR_MSG | TCL_APPEND_VALUE
-		| TCL_LIST_ELEMENT | TCL_TRACE_READS);
+		| TCL_LIST_ELEMENT);
 	goto doStoreStk;
 
     case INST_LAPPEND_ARRAY_STK:
 	valuePtr = OBJ_AT_TOS; /* value to append */
 	part2Ptr = OBJ_UNDER_TOS;
 	storeFlags = (TCL_LEAVE_ERR_MSG | TCL_APPEND_VALUE
-		| TCL_LIST_ELEMENT | TCL_TRACE_READS);
+		| TCL_LIST_ELEMENT);
 	goto doStoreStk;
 
     case INST_APPEND_STK:
@@ -2947,14 +2947,14 @@
 	opnd = TclGetUInt4AtPtr(pc+1);
 	pcAdjustment = 5;
 	storeFlags = (TCL_LEAVE_ERR_MSG | TCL_APPEND_VALUE
-		| TCL_LIST_ELEMENT | TCL_TRACE_READS);
+		| TCL_LIST_ELEMENT);
 	goto doStoreArray;
 
     case INST_LAPPEND_ARRAY1:
 	opnd = TclGetUInt1AtPtr(pc+1);
 	pcAdjustment = 2;
 	storeFlags = (TCL_LEAVE_ERR_MSG | TCL_APPEND_VALUE
-		| TCL_LIST_ELEMENT | TCL_TRACE_READS);
+		| TCL_LIST_ELEMENT);
 	goto doStoreArray;
 
     case INST_APPEND_ARRAY4:
@@ -2996,14 +2996,14 @@
 	opnd = TclGetUInt4AtPtr(pc+1);
 	pcAdjustment = 5;
 	storeFlags = (TCL_LEAVE_ERR_MSG | TCL_APPEND_VALUE
-		| TCL_LIST_ELEMENT | TCL_TRACE_READS);
+		| TCL_LIST_ELEMENT);
 	goto doStoreScalar;
 
     case INST_LAPPEND_SCALAR1:
 	opnd = TclGetUInt1AtPtr(pc+1);
 	pcAdjustment = 2;
 	storeFlags = (TCL_LEAVE_ERR_MSG | TCL_APPEND_VALUE
-		| TCL_LIST_ELEMENT | TCL_TRACE_READS);
+		| TCL_LIST_ELEMENT);
 	goto doStoreScalar;
 
     case INST_APPEND_SCALAR4:
Index: generic/tclVar.c
===================================================================
RCS file: /cvsroot/tcl/tcl/generic/tclVar.c,v
retrieving revision 1.160.2.10
diff -u -r1.160.2.10 tclVar.c
--- generic/tclVar.c	31 Jul 2010 18:10:11 -0000	1.160.2.10
+++ generic/tclVar.c	1 Sep 2010 15:01:30 -0000
@@ -1815,8 +1815,10 @@
 
     /*
      * Invoke any read traces that have been set for the variable if it is
-     * requested; this is only done in the core by the INST_LAPPEND_*
-     * instructions.
+     * requested. This was done for INST_LAPPEND_* but that was inconsistent
+     * with the non-bc instruction, and would cause failures trying to
+     * lappend to any non-existing ::env var, which is inconsistent with
+     * documented behavior.  [Bug #3057639]
      */
 
     if ((flags & TCL_TRACE_READS) && ((varPtr->flags & VAR_TRACED_READ)
