I may have found a related problem:

The following appears in function list2cmdline():

            elif c == '"':
                # Double backspaces.
                result.append('\\' * len(bs_buf)*2)
                bs_buf = []
                result.append('\\"')

i.e. the character(s) being checked is a double quote, but the comment states 'Double backspaces'.  The code as it is (using Python25) causes a problem when trying to perform a Windows XP copy on a file with whitespace in it's name.  The problem does not occur if the double quote in the code above is replaced by 2 back ticks.