Change:
Kdenlive build fails because CMake can't find QtConcurrent. Error: It appears to have been broken by some changes made to qtbase but I am not familiar enough with it to know what specifically. Changes between success and first failure: Latest Hydra failure: cc Attempt to install Kdenlive System: NixOS: 17.09pre107928. (Hummingbird) Nix version: nix-env (Nix) 1.11.9 Nixpkgs version: "17.09pre107928." Sandboxing enabled: build-use-sandbox = true
You need to modify the to We should send a patch upstream. This must be a required change since QT5.8.
Fixed by:

Discussion:
<ins> { cabal, blazeHtml, deepseq, Elm, filepath, happstackServer, HTTP , mtl, parsec, transformers }: cabal.mkDerivation (self: { pname = "elm-server"; version = "0.8"; sha256 = "0mnxayfg54f5mr27sd1zw3xrdijppgvrz2yzzmhp07qc1jiyfald"; isLibrary = false; isExecutable = true; buildDepends = [ blazeHtml deepseq Elm filepath happstackServer HTTP mtl parsec transformers ]; meta = { homepage = "http://elm-lang.org"; description = "The Elm language server"; license = self.stdenv.lib.licenses.bsd3; platforms = self.ghc.meta.platforms; }; }) </ins>

<ins> { cabal, blazeHtml, blazeMarkup, cmdargs, deepseq, filepath, hjsmin , indents, json, mtl, pandoc, parsec, shakespeare, text , transformers }: cabal.mkDerivation (self: { pname = "Elm"; version = "0.8.0.3"; sha256 = "0zai8glmkiqramivgz405zh385cz166gpry2yl29g37dxpwxffzb"; isLibrary = true; isExecutable = true; buildDepends = [ blazeHtml blazeMarkup cmdargs deepseq filepath hjsmin indents json mtl pandoc parsec shakespeare text transformers ]; meta = { homepage = "http://elm-lang.org"; description = "The Elm language module"; license = self.stdenv.lib.licenses.bsd3; platforms = self.ghc.meta.platforms; }; }) </ins>

<ins> { cabal }: cabal.mkDerivation (self: { pname = "concatenative"; version = "1.0.1"; sha256 = "05xwqvcdnk8bsyj698ab9jxpa1nk23pf3m7wi9mwmw0q8n99fngd"; meta = { homepage = "https://patch-tag.com/r/salazar/concatenative/snapshot/current/content/pretty"; description = "A library for postfix control flow"; license = self.stdenv.lib.licenses.bsd3; platforms = self.ghc.meta.platforms; }; }) </ins>

<ins> { cabal, concatenative, mtl, parsec }: cabal.mkDerivation (self: { pname = "indents"; version = "0.3.3"; sha256 = "16lz21bp9j14xilnq8yym22p3saxvc9fsgfcf5awn2a6i6n527xn"; buildDepends = [ concatenative mtl parsec ]; meta = { homepage = "http://patch-tag.com/r/salazar/indents"; description = "indentation sensitive parser-combinators for parsec"; license = self.stdenv.lib.licenses.bsd3; platforms = self.ghc.meta.platforms; }; }) </ins>

compactStringFix = callPackage ../development/libraries/haskell/compact-string-fix {}; <ins> concatenative = callPackage ../development/libraries/haskell/concatenative {}; </ins> conduit = callPackage ../development/libraries/haskell/conduit {}; ConfigFile = callPackage ../development/libraries/haskell/ConfigFile {};

elerea = callPackage ../development/libraries/haskell/elerea {}; <ins> Elm = callPackage ../development/compilers/elm/elm.nix {}; elmServer = callPackage ../development/compilers/elm/elm-server.nix {}; </ins> emailValidate = callPackage ../development/libraries/haskell/email-validate {}; encoding = callPackage ../development/libraries/haskell/encoding {};

ieee754 = callPackage ../development/libraries/haskell/ieee754 {}; <ins> indents = callPackage ../development/libraries/haskell/indents {}; </ins> instantGenerics = callPackage ../development/libraries/haskell/instant-generics {}; ioChoice = callPackage ../development/libraries/haskell/io-choice {};