Avoid stalling for new networks

[dbratell]

I noticed that my client did nothing for a fair amount of time (minutes) just as a new network had become available. I assume the server is swamped with download requests so wouldn't it be better if the client kept working on the previous network until the download was complete?

[dubslow]

This appears to still be a problem, according to multiple people on Discord. I'm adding this to the "promote lc0" project, as client instability is most certainly a blocking problem

[mooskagh]

That's not a problem, surely not blocking.
The issue from June 3 is that client doesn't run training while downloading a new net.

[dubslow]

It's a problem, but surely not blocking. I wildly misunderstood what the issue claimed the first time.