Comment # 1 on bug 1023847 from Aurelien Aptel

The only thing linked against ncurses in general seems to be samba-regedit.

There is indeed code in the upstream build tool scripts that tries to use
ncurses5-config first, then ncurses6-config.

In source3/wscript_configure_system_ncurses:

    conf.find_program('ncurses5-config', var='NCURSES_CONFIG')
    if not conf.env.NCURSES_CONFIG:
        conf.find_program('ncurses6-config', var='NCURSES_CONFIG')

Which means just removing the ncurses5-config prog from ncurses-devel will
force the script to pick the ncurses6 config prog.

This behaviour is pretty old and has been around since at least samba 4.1 [1],
which means SLE12 and above.

1: git tag --contains 356b825 | grep samba-