Resolving dependencies...
Configuring mtl-2.2.1...
Building mtl-2.2.1...
Preprocessing library mtl-2.2.1...
ghc: can't find a package database at /home/builder/hackage-server/build-cache/tmp-install/packages.db
Failed to install mtl-2.2.1
cabal: Error: some packages failed to install:
NXT-0.1.5 depends on mtl-2.2.1 which failed to install.
mtl-2.2.1 failed during the building phase. The exception was:
ExitFailure 1