Apache Airflow version:
1.10.14

Kubernetes version (if you are using kubernetes) (use kubectl version):
1.19.4

Environment:

• Cloud provider or hardware configuration:
• OS (e.g. from /etc/os-release):
• Kernel (e.g. uname -a):
• Install tools: production docker image
• Others: python3.7

What happened:
I recently upgraded from 1.10.9 -> 1.10.14, and enabled both STORE_SERIALIZED_DAGS and STORE_DAG_CODE to True. Everything seems to work as expected, and the scheduler is able to execute the DAG and the tasks within. However, the "Code View" in the UI displays a very long hex string instead of the actual code.

\x66726f6d206461746574696...

I have narrowed it down to be an issue, only when dag file is stored within zip files. For example, my_dag.py and my_other_dag.py would show in the UI incorrectly in the following case:

├── my_dag.zip
│   ├── my_dag.py
│   └── utils.py
├── my_other_dag.zip
│   ├── my_other_dag.py

but this is fine:

├── my_dag.py
├── my_other_dag.py
├── utils.py

A quick look at the database also reflects the incorrectly parsed DAG code within the source_code column of the public.dag_code table. But the fact that the scheduler can execute the dag, and that the data column of the public.serialized_dag table contains the correct code, suggests that this issue is isolated only when storing within the dag_code table.

What you expected to happen:
I should expect the actual python code to show in UI

import os
...

How to reproduce it:
Create 2 similar dags (1 within zip and 1 unzipped) and place into root dags folder. The UI will display the dag2.py incorrectly, but work fine for dag1.py

├── opt/airflow/dags
│   ├── dag1.py
│   ├── dag2.zip
│   │   └── dag2.py