Avoid failure on transient requirements in CI image (#8892)
Avoid failure on transient requirements in CI image (#8892)

When you build from the scratch and some transient requirements
fail, the initial step of installation might fail.

We are now using latest valid constraints from the DEFAULT_BRANCH
branch to avoid it.
cfei18/incubator-airflow,Acehaidrey/incubator-airflow,bolkedebruin/airflow,wooga/airflow,DinoCow/airflow,apache/airflow,apache/incubator-airflow,nathanielvarona/airflow,cfei18/incubator-airflow,sekikn/incubator-airflow,Acehaidrey/incubator-airflow,nathanielvarona/airflow,wooga/airflow,dhuang/incubator-airflow,nathanielvarona/airflow,DinoCow/airflow,mrkm4ntr/incubator-airflow,mrkm4ntr/incubator-airflow,wooga/airflow,mistercrunch/airflow,apache/airflow,cfei18/incubator-airflow,airbnb/airflow,danielvdende/incubator-airflow,danielvdende/incubator-airflow,apache/airflow,lyft/incubator-airflow,apache/incubator-airflow,airbnb/airflow,mistercrunch/airflow,bolkedebruin/airflow,mistercrunch/airflow,DinoCow/airflow,sekikn/incubator-airflow,dhuang/incubator-airflow,Acehaidrey/incubator-airflow,lyft/incubator-airflow,sekikn/incubator-airflow,mrkm4ntr/incubator-airflow,bolkedebruin/airflow,mistercrunch/airflow,Acehaidrey/incubator-airflow,apache/airflow,bolkedebruin/airflow,cfei18/incubator-airflow,bolkedebruin/airflow,airbnb/airflow,apache/incubator-airflow,nathanielvarona/airflow,sekikn/incubator-airflow,DinoCow/airflow,apache/incubator-airflow,airbnb/airflow,nathanielvarona/airflow,nathanielvarona/airflow,danielvdende/incubator-airflow,dhuang/incubator-airflow,danielvdende/incubator-airflow,dhuang/incubator-airflow,cfei18/incubator-airflow,Acehaidrey/incubator-airflow,apache/airflow,danielvdende/incubator-airflow,danielvdende/incubator-airflow,mrkm4ntr/incubator-airflow,lyft/incubator-airflow,wooga/airflow,apache/airflow,Acehaidrey/incubator-airflow,cfei18/incubator-airflow,lyft/incubator-airflow