Removed the call to zsh

dotnet.nix

@@ -5,7 +5,5 @@ let
   pkgs = import (fetchTarball "channel:nixpkgs-unstable") { };
 in pkgs.mkShell {
   buildInputs = [ pkgs.dotnet-sdk_9 ];
-  shellHook = ''
-    exec zsh
-  '';
+  shellHook = "";
 }

rust-nightly.nix

@@ -9,7 +9,5 @@ stdenv.mkDerivation {
     # to use the latest nightly:
     nixpkgs.latest.rustChannels.nightly.rust
   ];
-  shellHook = ''
-    exec zsh
-  '';
+  shellHook = "";
 }

rust.nix

@@ -5,7 +5,5 @@ let
   pkgs = import (fetchTarball "channel:nixpkgs-unstable") { };
 in pkgs.mkShell {
   buildInputs = [ pkgs.cargo pkgs.rustc pkgs.zsh pkgs.bacon ];
-  shellHook = ''
-    exec zsh
-  '';
+  shellHook = "";
 }