### Please describe the problem.

git-annex fails to build in the NixOS builder

### What steps will reproduce the problem?

cabal build

### What version of git-annex are you using? On what operating system?

5.20150812

### Please provide any additional information below.

[The build log](http://hydra.cryp.to/build/1099681/nixlog/1/raw) has a full transcript of the build from one of the build machines, though I have reproduced this locally.

The pertinent bit of the log (which is *not* at the end, though I think that's just a capture-both-stderr-and-stdin thing, since it was at the end when I repro'd it:

[[!format sh """
Assistant/WebApp/Types.hs:39:1: ‘WebApp’ is not in scope at a reify
"""]]

If I'm reading things correctly (you can do some diffing of the inputs from [the page for the build](http://hydra.cryp.to/build/1099681)), I'm going to guess that it was the upgrade to yesod-1.4.14.

I'll continue to look into it, but it would seem to touch on TH and Yesod stuff with which I am largely unfamiliar.

> Fixed with mdorman's patch, [[done]] (will push a release in a day or 2) --[[Joey]]
