copy_fields "overwrite" flag does not work properly #10
Description
The current implementation of copy_fields has multiple "layers" of flag checks. There are 3 flags that can be used, either standalone or together: base, optional and overwrite. Currently, overwrite is ignored if optional is not present. This is incorrect behavior, which becomes apparent when processing certain scripts.
An example set of commands follows:
copy_node gameplay race_bin_challenge/6_19_1/speedtrap1 speedtrap race_bin_challenge/6_19_2/speedtrap1
copy_node gameplay race_bin_challenge/6_19_2/speedtrap1 speedtrap race_bin_challenge/6_19_2/speedtrap2
copy_fields gameplay race_bin_challenge/6_19_2/checkpoint1 race_bin_challenge/6_19_2/speedtrap1 overwrite
copy_fields gameplay race_bin_challenge/6_19_2/checkpoint2 race_bin_challenge/6_19_2/speedtrap2 overwrite