perkeep: Build with go 1.9

pkgs/applications/misc/perkeep/default.nix

···
-{ stdenv, lib, go_1_8, fetchzip, git }:
+{ stdenv, lib, go, fetchzip, git, fetchpatch, fetchFromGitHub, fetchgit }:
+
+# When perkeep is updated all deps in the let block should be removed
+let
+  gopherjs = fetchFromGitHub {
+    owner = "gopherjs";
+    repo = "gopherjs";
+    # Rev matching https://github.com/perkeep/perkeep/commit/2e46fca5cc1179dbd90bec49fec3870e6eca6c45
+    rev = "b40cd48c38f9a18eb3db20d163bad78de12cf0b7";
+    sha256 = "0kniz8dg5bymb03qriizza1h3gpymf97vsgq9vd222282pdj0vyc";
+  };
+
+  gotool = fetchFromGitHub {
+    owner = "kisielk";
+    repo = "gotool";
+    rev = "80517062f582ea3340cd4baf70e86d539ae7d84d";
+    sha256 = "14af2pa0ssyp8bp2mvdw184s5wcysk6akil3wzxmr05wwy951iwn";
+  };
+
+  gcimporter15 = fetchgit {
+    url = "https://go.googlesource.com/tools";
+    rev = "f8f2f88271bf2c23f28a09d288d26507a9503c97";
+    sha256 = "1pchwizx1sdli59g8r0p4djfjkchcvh8msfpp3ibvz3xl250jh0n";
+  };
 
+in
 stdenv.mkDerivation rec {
   name = "perkeep-${version}";
   version = "20170505";
···
     sha256 = "1vliyvkyzmhdi6knbh8rdsswmz3h0rpxdpq037jwbdbkjccxjdwa";
   };
 
-  buildInputs = [ git go_1_8 ];
+  # When perkeep is updated postPatch should be removed
+  postPatch = ''
+    rm -r ./vendor/github.com/gopherjs/gopherjs/
+    cp -a ${gopherjs} ./vendor/github.com/gopherjs/gopherjs
+    mkdir -p ./vendor/github.com/kisielk/
+    cp -a ${gotool} ./vendor/github.com/kisielk/gotool
+    mkdir -p ./vendor/golang.org/x/tools/go
+    cp -a ${gcimporter15}/go/gcimporter15 ./vendor/golang.org/x/tools/go/gcimporter15
+
+    substituteInPlace vendor/github.com/gopherjs/gopherjs/build/build.go \
+      --replace '"github.com/fsnotify/fsnotify"' 'fsnotify "camlistore.org/pkg/misc/fakefsnotify"'
+
+    substituteInPlace ./make.go \
+      --replace "goVersionMinor  = '8'" "goVersionMinor  = '9'" \
+      --replace "gopherJSGoMinor = '8'" "gopherJSGoMinor = '9'"
+  '';
+
+  buildInputs = [ git go ];
 
   goPackagePath = "";
   buildPhase = ''

pkgs/top-level/all-packages.nix

···
     openjpeg = openjpeg_1;
   };
 
-  perkeep = callPackage ../applications/misc/perkeep { };
+  perkeep = callPackage ../applications/misc/perkeep {
+    # Perkeep is very particular about which go version to build with.
+    go = go_1_9;
+  };
 
   canto-curses = callPackage ../applications/networking/feedreaders/canto-curses { };