[WM] fix memoization of core.async channels
[WM] fix memoization of core.async channels

OK, this was a fun one. What I *think* was going on here is that we were
memoizing the core.async channels returned by the search
fns. Sometimes (such as running the tests in my single-core Docker VM),
tests would fail on the second take from the memoed channel, which makes
sense. The craziest aspect is that, on my multi-core OS X host (I'm
assuming the number of cores has anything to do with this), the tests
passed. As though, if you hurry, you can take the same message from the
same channel twice in parallel on different threads. But who knows!

Anyway, this seems better?

democracyworks/electorate-works