Fix --start-at-task when skipping tasks with no name (#68951)

Using --start-at-task on a playbook with tasks with no name would fail
if those unnamed tasks were encountered before the targetted start task.

changelogs/fragments/68569-start-at-fix.yaml

@@ -0,0 +1,2 @@
+bugfixes:
+- Using --start-at-task would fail when it attempted to skip over tasks with no name.

lib/ansible/executor/play_iterator.py

@@ -201,7 +201,7 @@ class PlayIterator:
                     (s, task) = self.get_next_task_for_host(host, peek=True)
                     if s.run_state == self.ITERATING_COMPLETE:
                         break
-                    if task.name == play_context.start_at_task or fnmatch.fnmatch(task.name, play_context.start_at_task) or \
+                    if task.name == play_context.start_at_task or (task.name and fnmatch.fnmatch(task.name, play_context.start_at_task)) or \
                        task.get_name() == play_context.start_at_task or fnmatch.fnmatch(task.get_name(), play_context.start_at_task):
                         start_at_matched = True
                         break

test/integration/targets/play_iterator/aliases

@@ -0,0 +1 @@
+shippable/posix/group4

test/integration/targets/play_iterator/playbook.yml

@@ -0,0 +1,10 @@
+---
+- hosts: localhost
+  gather_facts: false
+  tasks:
+    - name:
+      debug:
+        msg: foo
+    - name: "task 2"
+      debug:
+        msg: bar

test/integration/targets/play_iterator/runme.sh

@@ -0,0 +1,5 @@
+#!/usr/bin/env bash
+
+set -eux
+
+ansible-playbook playbook.yml --start-at-task 'task 2' "$@"