Fix how revision is embedded so that AppImage isn't always recompiled

default.nix

@@ -4,7 +4,7 @@
   hostSystem ? buildSystem,
   pkgsNix ? (import ./nix/pkgs.nix),
 
-  revision ? "",
+  revision ? "dev",
   releaseName ? "dev",
 
   bootstrap ? null,
@@ -28,7 +28,6 @@ in rec {
     name = "isle-version";
 
     inherit buildSystem hostSystem revision releaseName;
-    repoSrc = ./.;
 
     nativeBuildInputs = [ pkgsNative.git ];
 
@@ -41,11 +40,6 @@ in rec {
 
       versionFile=version
 
-      if [ "$revision" = "" ]; then
-        cp -r "$repoSrc" repoSrcCp
-        revision="$(cd repoSrcCp && git rev-parse HEAD)"
-      fi
-
       echo "Release:         $releaseName"    >> "$versionFile"
       echo "Platform:        $hostSystem"     >> "$versionFile"
       echo "Git Revision:    $revision"       >> "$versionFile"

release.nix

@@ -1,5 +1,6 @@
 {
   releaseName,
+  revision,
 
   buildSystem ? builtins.currentSystem,
   pkgsNix ? (import ./nix/pkgs.nix),
@@ -12,7 +13,7 @@
   mkRelease = hostSystem: let
 
     appImage = ((import ./default.nix) {
-      inherit buildSystem hostSystem releaseName;
+      inherit buildSystem hostSystem releaseName revision;
     }).appImage;
 
   in pkgs.stdenv.mkDerivation {

release.sh

@@ -19,7 +19,10 @@ if [ -e "$out" ]; then
     exit 1
 fi
 
+revision=$(git rev-parse HEAD)
+
 result=$(nix-build \
+            --argstr revision "$revision" \
             --argstr releaseName "$releaseName" \
             --no-out-link \
             release.nix \