How to merge github wiki changes from one repository to another

Case:
User forked a repository on GitHub and wiki pages are also forked, user do changes to wiki, but there is no way to send pull request for wiki changes, but Wiki is just another sub repository in GitHub repo, so admin of original repository have to do merge manually.

Example:
source wiki: https://github.com/VadimPanasiuk/sevntu.checkstyle.wiki.git
target/original wiki: https://github.com/sevntu-checkstyle/sevntu.checkstyle.wiki.git

Source of wisdom for massive squash.

Commands:

git clone https://github.com/sevntu-checkstyle/sevntu.checkstyle.wiki.git

cd sevntu.checkstyle.wiki.git

git fetch https://github.com/VadimPanasiuk/sevntu.checkstyle.wiki.git master:master-Vadim

git checkout master-Vadim

#checkout to last non-Vadim's commit  

git reset --hard 34a2f8e627dd6209f4928b6f66a37368789ab492

# do massive squash of all Vadim's changes

git merge --squash HEAD@{1}          

git commit -m "How to use SevNTU Checkstyle in Intellij IDEA (markdown)"

git checkout master

# cherry-pick newly squashed  commit

git cherry-pick cbe1915a65d80769d56f4fbd9a60dd0b88c8c049    

git push

If wiki was forked from latest state of original wiki, you can do it a bit simpler:

git clone https://github.com/sevntu-checkstyle/sevntu.checkstyle.wiki.git

cd sevntu.checkstyle.wiki.git

git pull https://github.com/VadimPanasiuk/sevntu.checkstyle.wiki.git master

# squashing all Vadim's changes in one 

git push origin master

Git - merge till certain commit

Case: you need merge your master with with development branch but till certain commit(not till HEAD ) in development branch

it is simply:
-- I presume you are at development branch --
git checkout master
git merge 37e4218a4d51ad44952d30a5906cbe6b2e0a54d2

or do it by tag name:
git merge 0.5.10

and you will merge till this(37e421) commit, that is located in development branch.