yesod devel compiles after change, but doesn't actually reflect change

Question

This happens in all handlers, but as an example, I have a simple handler I edit in vim:

getListingR :: Handler Html
getListingR = do
  defaultLayout $ do
    setTitle "Thing"
    [whamlet|<p>Content|]

yesod devel launches a server, and sometimes serves this.

But then, when I change the setTitle call (not even the quasiquoter, just the literal string), the server process recognizes the change, starts the recompile, and serves up the "wait while recompiling" page.

BUT when finished, it goes back to serving up the old content.

I said 'sometimes' earlier because it doesn't seem to pick up the newest changes on a fresh yesod devel launch. A cabal build seems to always pick up changes.

I am running GHC 7.10.1, in a cabal sandbox locked to stackage nightly.