Fix appimagetool build

nix/appimagetool.nix

@@ -2,39 +2,28 @@
 
 let
 
-  version = "745";
+  version = "765";
 
   cpuArch = stdenv.buildPlatform.parsed.cpu.name;
 
-  src = {
-
-    "x86_64" = fetchurl {
-      url = "https://github.com/probonopd/go-appimage/releases/download/continuous/appimagetool-${version}-x86_64.AppImage";
-      sha256 = "sha256-HQ7d9LQDaPm6sGZ5boWZdmGTNqiGN9NWHUWPiDhl2Xc=";
-    };
-
-    "aarch64" = fetchurl {
-      url = "https://github.com/probonopd/go-appimage/releases/download/continuous/appimagetool-${version}-aarch64.AppImage";
-      sha256 = "sha256-VvH2qXULliCiyFrisaIJbM0ApXp++ZAtxHiS6FM3XT0=";
-    };
-
-    "armv7l" = fetchurl {
-      url = "https://github.com/probonopd/go-appimage/releases/download/continuous/appimagetool-${version}-armhf.AppImage";
-      sha256 = "sha256-ytJjN2dLYOSwqCCFZvqnt+wt2wX/lZ1R+nVz5C+Akvo=";
-    };
-
-    "i686" = fetchurl {
-      url = "https://github.com/probonopd/go-appimage/releases/download/continuous/appimagetool-${version}-i686.AppImage";
-      sha256 = "sha256-GLEhn3dcrwdU3mG0lB6H7PQ5JwEIGqWlGrO1IifeQv4=";
-    };
+  srcDir = ./go-appimage;
 
+  # https://github.com/probonopd/go-appimage
+  # The author of go-appimage has set up some crazy continuous integration build
+  # system with github, which is really cool, except that it doesn't preserve
+  # any older builds of the project. And it's pretty difficult to build it
+  # ourselves. So fuck it, just embed a tarball into the repo.
+  src = {
+    "x86_64" = "${srcDir}/appimagetool-${version}-x86_64.AppImage";
+    "aarch64" = "${srcDir}/go-appimage/appimagetool-${version}-aarch64.AppImage";
+    "armv7l" = "${srcDir}/go-appimage/appimagetool-${version}-armhf.AppImage";
+    "i686" = "${srcDir}/go-appimage/appimagetool-${version}-i686.AppImage";
   }."${cpuArch}";
 
 in stdenv.mkDerivation rec {
 
   pname = "go-appimage";
   inherit version src;
-
   sourceRoot = "squashfs-root";
 
   unpackPhase = ''