[Nix-dev] ghcHEAD broken?

[Kosyrev Serge]

Good evening!

I'm trying to nix-shell into an environment constructed from
pkgs.haskell.packages.ghcHEAD, but get a failure to build the ghc wrapper:

,----
| [deepfire at andromedae:~/src/mood]$ nix-store --realise /nix/store/w3gnqdxlxv9dsrvknvy2pwpyf0cq91y3-ghc-7.11.20150705.drv
| these derivations will be built:
|   /nix/store/w3gnqdxlxv9dsrvknvy2pwpyf0cq91y3-ghc-7.11.20150705.drv
| building path(s) ‘/nix/store/vps1c9svh52zhb7crw41k2nvhgdngivd-ghc-7.11.20150705’
| created 42 symlinks in user environment
| ghc-pkg: /nix/store/vps1c9svh52zhb7crw41k2nvhgdngivd-ghc-7.11.20150705/lib/ghc-7.11.20150705/package.conf.d/package.cache: you don't have permission to modify this file
| builder for ‘/nix/store/w3gnqdxlxv9dsrvknvy2pwpyf0cq91y3-ghc-7.11.20150705.drv’ failed with exit code 1
| error: build of ‘/nix/store/w3gnqdxlxv9dsrvknvy2pwpyf0cq91y3-ghc-7.11.20150705.drv’ failed
`----

Is it known-broken in this respect?

-- 
respectfully,
Косырев Серёга
--
“And those who were seen dancing were thought to be insane
 by those who could not hear the music.”
 – Friedrich Wilhelm Nietzsche