I am thinking these two macros would be useful.
CMD_CP_UPDATE is to copy files only if file is newer.
CMD_IGNORERR is to reset the OS error value to the no error value.
I have only tested them on Windows 32 bit at this time.
I tested them using these pre build steps
CMD /C dir
$(CMD_MKDIR) "a/b/c" > $(CMD_NULL) $(CMD_IGNORERR)
$(CMD_CP_UPDATE) *.cbp a
Attached Git formatted patch.
Tim S.