devshell: Allow deploy-multi without options

devshell/commands.nix

@@ -144,7 +144,11 @@ in
       help = "Deploy multiple flakes at once";
       command = ''
         for f in $@; do
+          if [ -n "''${O:-}" ]; then
             deploy "$O" $f
+          else
+            deploy $f
+          fi
         done
       '';
     }

nixos/modules/tmproot.nix

@@ -145,6 +145,7 @@ in
             # Also the script runs before impermanence does.
             "/var/lib/nixos"
             "/var/lib/systemd"
+            "/var/cache/man"
 
             { directory = "/root/.cache/nix"; mode = "0700"; }
             # Including these unconditionally due to infinite recursion problems...