[#7472] ticket:633 Prevent lots of test failures, when tests run together
[#7472] ticket:633 Prevent lots of test failures, when tests run together

Mocking `c` in `TestThread` somehow affects other tests. They see mock
object instead of real context and can't encode some stuff to bson,
e.g. `c.app.config._id`.

heiths/allura,apache/allura,apache/allura,heiths/allura,apache/allura,lym/allura-git,heiths/allura,lym/allura-git,apache/allura,heiths/allura,heiths/allura,apache/allura,lym/allura-git,lym/allura-git,lym/allura-git