Don't use 'git -C' (it's too new?)

spec/support/seed_helper.rb

@@ -10,10 +10,10 @@ module SeedHelper
     FileUtils.mkdir_p(SUPPORT_PATH)
     system(*%W(git clone --bare https://gitlab.com/gitlab-org/gitlab-git-test.git #{TEST_REPO_PATH}), chdir: SUPPORT_PATH)
     File.open(File.join(TEST_REPO_PATH, 'refs/heads/master'), 'w') { |f| f.puts SeedRepo::LastCommit::ID }
-    IO.popen(%W(git -C #{TEST_REPO_PATH} tag)).read.each_line do |tag|
+    IO.popen(%W(git tag), chdir: TEST_REPO_PATH).read.each_line do |tag|
       tag.chomp!
       unless SeedRepo::Repo::TAGS.include?(tag)
-        system(*%W(git -C #{TEST_REPO_PATH} tag -d -- #{tag}))
+        system(*%W(git tag -d -- #{tag}), chdir: TEST_REPO_PATH)
       end
     end
   end