[AIRFLOW-102]: Fix broken test test_complex_template

[withnale]

Dear Airflow Maintainers,

Please accept this PR that addresses the following issues:

• https://issues.apache.org/jira/browse/AIRFLOW-102

Reminders for contributors:

• Your PR's title must reference an issue on Airflow's JIRA. For example, a PR called "[AIRFLOW-1] My Amazing PR" would close JIRA issue Improving the search functionality in the graph view #1. Please open a new issue if required!
• You must add an Apache License header to all new files.
• Please squash your commits when possible and follow the 7 rules of good Git commits.

[withnale]

Any update on merging this?