Even when data/milestones.json exists, the project doesn't start

[karlcow]

Steps to reproduce:

1. Disconnect from the network
2. Start your environment
3. Check that data/milestones.json exists
4. start the project.

Actual:

🐝 10:07:14 ~/code/webcompat.com
→ python run.py
Statuses Initialization…
Fetching milestones from Github…
Milestones are not initialized. Check logs.

Our current logic is to try to fetch the milestones online, and if it the network request fails to fallback on the data/milestones.json. This has consequences.

1. The project can't start if the user is offline even with the right data.
2. The project can't start if the GitHub API received already too many requests and data/milestones.json doesn't already exist. (This happened during All Hands.)

We could invert the logic by checking first data/milestones.json and fetching online if it doesn't exist. It would be more logical at least in LOCALHOST mode where we have probably a version of the data handy. The frequency of actions seem to be in favor of data/ first and then network second.

This would partially solves #2518

@miketaylr for input/feedback

[miketaylr]

We could invert the logic by checking first data/milestones.json and fetching online if it doesn't exist. It would be more logical at least in LOCALHOST mode where we have probably a version of the data handy.

This sounds reasonable to me.