Does not respect the GHC option -B.

[fmap]

% ghci -B/nix/store/hfbh2jpdky9f72c7x3gqswj4q0clm7b2-haskell-env-ghc-7.6.3/lib/ghc-7.6.3/ src/Text/Taggy/Lens.hs 
GHCi, version 7.6.3: http://www.haskell.org/ghc/  :? for help
Loading package ghc-prim ... linking ... done.
Loading package integer-gmp ... linking ... done.
Loading package base ... linking ... done.
[1 of 1] Compiling Text.Taggy.Lens  ( src/Text/Taggy/Lens.hs, interpreted )
Ok, modules loaded: Text.Taggy.Lens.
λ: 
% doctest -B/nix/store/hfbh2jpdky9f72c7x3gqswj4q0clm7b2-haskell-env-ghc-7.6.3/lib/ghc-7.6.3/ src/Text/Taggy/Lens.hs 
doctest: unrecognized option `-B/nix/store/hfbh2jpdky9f72c7x3gqswj4q0clm7b2-haskell-env-ghc-7.6.3/lib/ghc-7.6.3/'
Try `doctest --help' for more information.
%

@sol suspects this is a bug in the GHC API.