This is a unique function call in CMake, and it was likely a
programming error when introduced. All other similar calls to
ReadListFile use a null first paramter.
The effect of this patch is to no-longer define CMAKE_PARENT_LIST_FILE
to the config file itself while evaluating it.
The ReadListFile method also no longer hits a condition that it uses
CollapseFullPath on the input file. However, as cpack does not
set the StartDirectory anyway, this has no effect. See bug 15522.
fc7ab8874b