replace `is_ancestor` with `ancestor?`

lib/gitlab/checks/force_push.rb

@@ -12,7 +12,7 @@ module Gitlab
             !project
               .repository
               .gitaly_commit_client
-              .is_ancestor(oldrev, newrev)
+              .ancestor?(oldrev, newrev)
           else
             Gitlab::Git::RevList.new(
               path_to_repo: project.repository.path_to_repo,

lib/gitlab/git/repository.rb

@@ -440,7 +440,7 @@ module Gitlab
       # Returns true is +from+ is direct ancestor to +to+, otherwise false
       def ancestor?(from, to)
-        gitaly_commit_client.is_ancestor(from, to)
+        gitaly_commit_client.ancestor?(from, to)
       end
       # Return an array of Diff objects that represent the diff

lib/gitlab/gitaly_client/commit_service.rb

@@ -22,7 +22,7 @@ module Gitlab
         end
       end
-      def is_ancestor(ancestor_id, child_id)
+      def ancestor?(ancestor_id, child_id)
         request = Gitaly::CommitIsAncestorRequest.new(
           repository: @gitaly_repo,
           ancestor_id: ancestor_id,