Fix gammapy download for Python 2 #1836
This PR fixes multiprocess download in Python 2.7
It also disables unicode-literals warnings in CLI apps
@Bultako - Thanks!
Overall I think this code would separate by splitting the functionality in two classes.
One that has our specific stuff of figuring out which files to download.
A second one that is a general
The first class would compute the "manifest" or "request" or "plan" of files to download, and pass it to the second class to execute.
At the moment the complexity of the one class is pretty high, and I think that way to structure the code could make it a little easier to read and maintain.
Concerning folder creation, I still think a first phase where folders are created, and only then the parallel download and file write might be better. We want bullet-proof here without the possibility of race conditions. Not works 99% of the time, but then sometimes fails with weird error for some users.
You don't have to do it now, I'm interested to review and pair-code on that part of the code next week.