[ARCH] Arch_Roof fix for adjust_list_len function
[ARCH] Arch_Roof fix for adjust_list_len function

LGTM code analysis did not like that the adjust_list_len function would mutate default list values. De function now always clones the list.
See: https://forum.freecadweb.org/viewtopic.php?f=23&t=55943
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