Merge branch 'update-gitlab-git' into 'master'

Updated gitlab_git to 10.6.3

## What does this MR do?

This updated gitlab_git to 10.6.3

## Does this MR meet the acceptance criteria?

- [x] ~~[CHANGELOG](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CHANGELOG) entry added~~
- Tests
  - [x] All builds are passing
- [x] Conform by the [style guides](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CONTRIBUTING.md#style-guides)
- [x] Branch has no merge conflicts with `master` (if you do - rebase it please)
- [x] [Squashed related commits together](https://git-scm.com/book/en/Git-Tools-Rewriting-History#Squashing-Commits)

## What are the relevant issue numbers?

See merge request !6132

Gemfile

@@ -53,7 +53,7 @@ gem 'browser', '~> 2.2'
 
 # Extracting information from a git repository
 # Provide access to Gitlab::Git library
-gem 'gitlab_git', '~> 10.5'
+gem 'gitlab_git', '~> 10.6.3'
 
 # LDAP Auth
 # GitLab fork with several improvements to original library. For full list of changes

Gemfile.lock

@@ -279,7 +279,7 @@ GEM
       diff-lcs (~> 1.1)
       mime-types (>= 1.16, < 3)
       posix-spawn (~> 0.3)
-    gitlab_git (10.5.0)
+    gitlab_git (10.6.3)
       activesupport (~> 4.0)
       charlock_holmes (~> 0.7.3)
       github-linguist (~> 4.7.0)
@@ -858,7 +858,7 @@ DEPENDENCIES
   github-linguist (~> 4.7.0)
   github-markup (~> 1.4)
   gitlab-flowdock-git-hook (~> 1.0.1)
-  gitlab_git (~> 10.5)
+  gitlab_git (~> 10.6.3)
   gitlab_meta (= 7.0)
   gitlab_omniauth-ldap (~> 1.2.1)
   gollum-lib (~> 4.2)