Empty consensus weights in consensus footer

[robgjansen]

When one of the positions has 0 bandwidth, which can happen in small Tor networks, Tor fails to produce weights in the consensus footer which causes it to default to an older path selection algorithm.

I proposed a fix in Tor here:
https://trac.torproject.org/projects/tor/ticket/14881

More info about this bug, see these mailing list threads:
http://mailman.cs.umn.edu/archives/shadow-support/2015-November/000462.html
http://mailman.cs.umn.edu/archives/shadow-support/2015-December/000465.html

As stated in the threads, if you use the strict flag assignment feature that I proposed in https://trac.torproject.org/projects/tor/ticket/14882 and was merged into Tor 0.2.7 stable, then we can set the flags properly to avoid running into this issue.