2 - Teach bridge-using clients to avoid 0.2.2 bridges when making
3 microdescriptor-related dir requests, and only fall back to normal
4 descriptors if none of their bridges can handle microdescriptors
5 (as opposed to the fix in ticket 4013, which caused them to fall
6 back to normal descriptors if *any* of their bridges preferred
7 them). Resolves ticket 4994.