Can't build or install hydra

In hyrda/master I try the ./dev-shell command. I get 103 failed tests and the following traceback:

iles=305, Tests=26572, 177 wallclock secs ( 3.70 usr  0.33 sys + 143.15 cusr 15.66 csys = 162.84 CPU)
Result: FAIL
Failed 1/305 test programs. 1/26572 subtests failed.
Makefile:1715: recipe for target 'test_dynamic' failed
make: *** [test_dynamic] Error 255
builder for ‘/nix/store/izmcc4hrhdswnqn5cdid4aqkprl7xdnr-perl-DBIx-Class-0.082801.drv’ failed with exit code 2
cannot build derivation ‘/nix/store/l1cvb9z0si3gzryldngdl0l6h1jcfaz8-perl-Catalyst-Authentication-Store-DBIx-Class-0.1506.drv’: 1 dependencies couldn't be built
cannot build derivation ‘/nix/store/2qf1cdnx7fz8idx7lngpz3xlwqs3v7vd-hydra-perl-deps.drv’: 1 dependencies couldn't be built
cannot build derivation ‘/nix/store/5cpszmrwr191xg07wrpba5y5x4klgq88-hydra-0.1pre1234-abcdef.drv’: 1 dependencies couldn't be built
cannot build derivation ‘/nix/store/7nx6hai8gb47akmm57g2snd42pqjgy7s-system-path.drv’: 1 dependencies couldn't be built
cannot build derivation ‘/nix/store/kycp8dw36xica91a51wja54ywmx85w5k-unit-hydra-evaluator.service.drv’: 1 dependencies couldn't be built
cannot build derivation ‘/nix/store/l7dwsdhm3bqa5bvm09qc4ky231mwsjzy-unit-hydra-init.service.drv’: 1 dependencies couldn't be built
cannot build derivation ‘/nix/store/05qw6pbgjfaj8ywwn02gsnykphazh8l0-unit-hydra-queue-runner.service.drv’: 1 dependencies couldn't be built
cannot build derivation ‘/nix/store/hsr154papmy4ghqvb9c5ismbmr5ab4g5-unit-hydra-server.service.drv’: 1 dependencies couldn't be built
cannot build derivation ‘/nix/store/76qw96adw41jnrjdn88r2fjk7ami7hsr-unit-hydra-update-gc-roots.service.drv’: 1 dependencies couldn't be built
cannot build derivation ‘/nix/store/b4yrmmps17w69gpi87rkx83g9hplhfrv-nixos-15.05pre61966.75ebc3c.drv’: 1 dependencies couldn't be built

Nix channel:

nix-channel --list
nixpkgs http://nixos.org/channels/nixpkgs-unstable

NixOS / hydra

Can't build or install hydra #215