test: patch the interpreter instead of invoking python directly

pkgs/e11sync.nix

@@ -43,6 +43,7 @@ stdenv.mkDerivation {
   '';
   passthru.tests.unit =
     runCommand "e11sync-test" {
+      src = self;
       buildInputs = [
         python3Packages.django_5
         python3Packages.django-compressor
@@ -50,9 +51,11 @@ stdenv.mkDerivation {
         dart-sass
       ];
     } ''
-      mkdir -p $out
-      cd ${self}/app
+      unpackPhase
+      patchShebangs --build $sourceRoot/app/manage.py
+      cd $sourceRoot
       export GEOIP_PATH="${geoip-archive}"
-      ${python3}/bin/python3 ./manage.py test
+      app/manage.py test app
+      mkdir -p $out
     '';
 }