Unfortunately version 1.10 has been killed in https://github.com/freebsd/freebsd-ports/commit/78d03534d7899a27f3a74cb078ccc192a61113ff not taking into account that both 1.9 and 1.10 are LTS releases while 1.11 will only live for 6 months. Please readd 1.10 just like 1.9 is right now selectable via WITH_SUBVERSION_VER.
Are you ready to be maintainer of 1.10 port?
(In reply to Lev A. Serebryakov from comment #1)
That would be OK for me, 1.10.x does not change that often and I do already mantain other ports too.
A commit references this bug:
Date: Thu Apr 25 16:28:48 UTC 2019
New revision: 500031
Add LTS version of subversion to ports.
I've added such port.