pytype: work around wrong ImportError flagging As documented in https://github.com/google/pytype/issues/163, newer versions of Pytype do not understand caught `ImportError`, so we temporarily ignore them where applicable.

zeroconf: fix boolean return value This was (wrongly) flagged by Pytype as being undefined since it doesn't seem to understand `try` blocks. However, the caller is expecting a boolean and the fix to appease Pytype is simple, so we do both.

Backout accidental publication of a large range of revisions I accidentally published 25e7f9dcad0f::bd1483fd7088, this is the inverse.