fzf displayed --header-lines inconsistently depending on the presence of borders:
# --header and --header-lines co-located
seq 10 | fzf --header-lines 3 --header "$(seq 101 103)" --header-first
# --header and --header-lines separated
seq 10 | fzf --header-lines 3 --header "$(seq 101 103)" --header-first --header-lines-border
This commit fixes the inconsistency with the following logic:
* If only one of --header or --header-lines is provided, --header-first
applies to that single header.
* If both are present, --header-first affects only the regular --header,
not --header-lines.
39db026161