The variable REVIEW_LOG_DIR and REVIEW_SCRIPT_DIRS and REVIEW_EXT_DIRS are used with defaults according to the XDG spec, including the variables XDG_CONFIG_HOME and XDG_DATA_HOME. It would easier to use f-r if we just removed the REVIEW variables and just trusted the XDG ones instead. At least, it would be easier to write the manpage
Fixed in e566c24bf67078092bb9