[man bug?] git rebase --preserve-merges

The man page for git rebase mentions "--preserve-merges" command line
option but this option does not seems to be available.

Also if this option is specified, the following usage statement is printed:

Usage: git rebase [--interactive | -i] [-v] [--onto <newbase>]
<upstream> [<branch>]

And this usage statement does not mention -m and -s options that seems
to be available. I assume that the problem is the obsolete
documentation.

Regards,
Constantine