Remove ENV['USE_SYSTEM_GIT_FOR_FETCH'] support

ee/changelogs/unreleased/5224-remove-use_system_git_for_fetch.yml

+---
+title: Use of ENV['USE_SYSTEM_GIT_FOR_FETCH'] is no longer supported
+merge_request:
+author:
+type: removed

lib/gitlab/git/gitlab_projects.rb

@@ -73,32 +73,15 @@ module Gitlab
       end
 
       def fetch_remote(name, timeout, force:, tags:, ssh_key: nil, known_hosts: nil, prune: true)
-        tags_option = tags ? '--tags' : '--no-tags'
-
         logger.info "Fetching remote #{name} for repository #{repository_absolute_path}."
-        cmd = %W(#{git_fetch_binary} fetch #{name} --quiet)
-        cmd << '--prune' if prune
-        cmd << '--force' if force
-        cmd << tags_option
+        cmd = fetch_remote_command(name, tags, prune, force)
 
         setup_ssh_auth(ssh_key, known_hosts) do |env|
-          success = run_with_timeout(cmd, timeout, repository_absolute_path, env)
-
-          unless success
-            logger.error "Fetching remote #{name} for repository #{repository_absolute_path} failed."
+          run_with_timeout(cmd, timeout, repository_absolute_path, env).tap do |success|
+            unless success
+              logger.error "Fetching remote #{name} for repository #{repository_absolute_path} failed."
+            end
           end
-
-          success
-        end
-      end
-
-      # This is a workaround for Geo until we can ship git 2.16
-      # See https://gitlab.com/gitlab-org/gitlab-ee/issues/5214
-      def git_fetch_binary
-        if ENV['USE_SYSTEM_GIT_FOR_FETCH'] == '1'
-          '/usr/bin/git'
-        else
-          Gitlab.config.git.bin_path
         end
       end
 
@@ -224,6 +207,14 @@ module Gitlab
 
       private
 
+      def fetch_remote_command(name, tags, prune, force)
+        %W(#{Gitlab.config.git.bin_path} fetch #{name} --quiet).tap do |cmd|
+          cmd << '--prune' if prune
+          cmd << '--force' if force
+          cmd << (tags ? '--tags' : '--no-tags')
+        end
+      end
+
       def git_import_repository(source, timeout)
         # Skip import if repo already exists
         return false if File.exist?(repository_absolute_path)

spec/lib/gitlab/git/gitlab_projects_spec.rb

@@ -160,20 +160,6 @@ describe Gitlab::Git::GitlabProjects do
         expect(key.string).to eq('KNOWN HOSTS')
       end
     end
-
-    context 'with USE_SYSTEM_GIT_FOR_FETCH env' do
-      let(:cmd) { %W(/usr/bin/git fetch #{remote_name} --quiet --prune --tags) }
-
-      before do
-        stub_env('USE_SYSTEM_GIT_FOR_FETCH', '1')
-      end
-
-      it 'uses system git' do
-        stub_spawn(cmd, 600, tmp_repo_path, {}, success: true)
-
-        is_expected.to be_truthy
-      end
-    end
   end
 
   describe '#import_project' do