Change to nette/tester@v0.9.1 because current @dev reference (dev-master f2ae772) could not be checked out from nette/test repository.

composer install --no-interaction --dev
Loading composer repositories with package information
Installing dependencies (including require-dev)
  - Installing nette/tester (dev-master f2ae772)
    Cloning f2ae772f0e90f418ce290f478ef34b20bbf1144d

  [RuntimeException]
  Failed to execute git checkout 'f2ae772f0e90f418ce290f478ef34b20bbf1144d' &
  & git reset --hard 'f2ae772f0e90f418ce290f478ef34b20bbf1144d'

  fatal: reference is not a tree: f2ae772f0e90f418ce290f478ef34b20bbf1144d