I tested branch creation with gitlab-ce with my 8.9 instance, no problem.
[user01@server01 ws]$ git clone g...@mygit.test.com:USER01/test01.git
Cloning into 'test01'...
warning: You appear to have cloned an empty repository.
[user01@server01 ws]$ cd test01/
[user01@server01 test01]$ ls
[user01@server01 test01]$ ls
[user01@server01 test01]$ git checkout -b develop
Switched to a new branch 'develop'
[user01@server01 test01]$ touch develop.txt
[user01@server01 test01]$ echo test >> develop.txt
[user01@server01 test01]$ git add develop.txt;git commit develop.txt -m "adding develop.txt"
[develop (root-commit) fd16b39] adding develop.txt
1 file changed, 1 insertion(+)
create mode 100644 develop.txt
[user01@server01 test01]$ git push origin develop
Counting objects: 3, done.
Writing objects: 100% (3/3), 231 bytes | 0 bytes/s, done.
Total 3 (delta 0), reused 0 (delta 0)
To g...@mygit.test.com:USER01/test01.git
* [new branch] develop -> develop
[user01@server01 test01]$