memoize get-dependencies

get-dependencies is expensive and sometimes gets called multiple times
with the same arguments. This pretty consistently knocks a couple
tenths of a second off of the extremely common
 `lein repl < /dev/null`.
Merge remote-tracking branch 'ryfow/memoize-get-dependencies'

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Some more don't-warn-when-missing profiles.
Fix a bunch of tests from reorg-repl.