fix race and updating local mounted repositories

common/lib/dependabot/file_fetchers/base.rb

@@ -69,6 +69,7 @@ def files
       end
 
       def commit
+        return cloned_commit if cloned_commit
         return source.commit if source.commit
 
         branch = target_branch || default_branch_for_repo
@@ -473,6 +474,16 @@ def _fetch_file_content_from_github(path, repo, commit)
       end
       # rubocop:enable Metrics/AbcSize
 
+      def cloned_commit
+        return if repo_contents_path.nil? || !File.directory?(File.join(repo_contents_path, ".git"))
+
+        SharedHelpers.with_git_configured(credentials: credentials) do
+          Dir.chdir(repo_contents_path) do
+            return SharedHelpers.run_shell_command("git rev-parse HEAD")&.strip
+          end
+        end
+      end
+
       def default_branch_for_repo
         @default_branch_for_repo ||= client_for_provider.
                                      fetch_default_branch(repo)

updater/lib/dependabot/file_fetcher_job.rb

@@ -10,9 +10,9 @@ class FileFetcherJob < BaseJob
     def perform_job
       begin
         connectivity_check if ENV["ENABLE_CONNECTIVITY_CHECK"] == "1"
+        clone_repo_contents
         base_commit_sha
         dependency_files
-        clone_repo_contents
       rescue StandardError => e
         if Octokit::RATE_LIMITED_ERRORS.include?(e.class)
           remaining = rate_limit_error_remaining(e)
@@ -94,12 +94,14 @@ def base_commit_sha
     end
 
     def file_fetcher
+      return @file_fetcher if defined? @file_fetcher
+
       args = {
         source: job.source,
         credentials: job_definition.fetch("credentials", []),
         options: job.experiments
       }
-      args[:repo_contents_path] = Environment.repo_contents_path if job.clone?
+      args[:repo_contents_path] = Environment.repo_contents_path if job.clone? || job.already_cloned?
       @file_fetcher ||=
         Dependabot::FileFetchers.for_package_manager(job.package_manager).
         new(**args)

updater/lib/dependabot/job.rb

@@ -43,6 +43,13 @@ def clone?
         Dependabot::Utils.always_clone_for_package_manager?(@package_manager)
     end
 
+    def already_cloned?
+      return unless Environment.repo_contents_path
+
+      # For testing, the source repo may already be mounted.
+      @already_cloned ||= File.directory?(File.join(Environment.repo_contents_path, ".git"))
+    end
+
     def lockfile_only?
       @lockfile_only
     end