Use Gitlab::Git instead of Ci::Git

app/models/ci/commit.rb

@@ -53,7 +53,7 @@ module Ci
     end
 
     def valid_commit_sha
-      if self.sha == Ci::Git::BLANK_SHA
+      if self.sha == Gitlab::Git::BLANK_SHA
         self.errors.add(:sha, " cant be 00000000 (branch removal)")
       end
     end

app/services/create_commit_builds_service.rb

@@ -9,14 +9,14 @@ class CreateCommitBuildsService
       return false
     end
 
-    ref = origin_ref.gsub(/\Arefs\/(tags|heads)\//, '')
+    ref = Gitlab::Git.ref_name(origin_ref)
 
     # Skip branch removal
-    if sha == Ci::Git::BLANK_SHA
+    if sha == Gitlab::Git::BLANK_SHA
       return false
     end
 
-    tag = origin_ref.start_with?('refs/tags/')
+    tag = Gitlab::Git.tag_ref?(origin_ref)
     commit = project.ensure_ci_commit(sha)
     unless commit.skip_ci?
       commit.update_committed!

lib/ci/git.rb

@@ -1,5 +0,0 @@
-module Ci
-  module Git
-    BLANK_SHA = '0' * 40
-  end
-end