Fix [e38dce74e2]: Command line built with list not properly quoted

Author: jan.nijtmans

generic/tclListObj.c

@@ -1776,6 +1776,16 @@ Tcl_ListObjAppendList(
     }
 
     if (elemCount <= 0) {
+	/*
+	 * Note that when elemCount <= 0, this routine is logically a
+	 * no-op, removing and adding no elements to the list. However, by removing
+	 * the string representation, we get the important side effect that the
+	 * resulting listPtr is a list in canonical form. This is important.
+	 * Resist any temptation to optimize this case further. See bug [e38dce74e2].
+	 */
+	if (!ListObjIsCanonical(toObj)) {
+	    TclInvalidateStringRep(toObj);
+	}
 	/* Nothing to do. Note AFTER check for list above */
 	return TCL_OK;
     }

tests/list.test

@@ -64,6 +64,16 @@ test list-1.30 {basic null treatment} {
     set e "\x00abc xyz"
     string equal $l $e
 } 1
+test list-1.31 {bug [e38dce74e2]} {
+    set l #foo
+    set e {}
+    list {*}$l {*}$e
+} {{#foo}}
+test list-1.32 {bug [e38dce74e2]} {
+    set l " #foo"
+    set e {}
+    list {*}$l {*}$e
+} {{#foo}}
 
 # For the next round of tests create a list and then pick it apart
 # with "index" to make sure that we get back exactly what went in.