Propagate morph success/failure out of update-deployment

Fixes #74 (closed)

nixos/modules/update-deployment

@@ -92,7 +92,9 @@ export NIX_PATH="nixpkgs=$(nix eval "(import ${CHECKOUT}/nixpkgs-2105.nix { }).p
 if morph deploy "${CHECKOUT}"/morph/grid/"${GRIDNAME}"/grid.nix switch --on "$(hostname)"; then
     # The deployment succeeded.  Record success along with context we pre-computed.
     echo "${LOG_MESSAGE} OK" >> ${HOME}/updates.txt
+    exit 0
 else
     # Oops.  Not so fortunate.  Record failure.
     echo "${LOG_MESSAGE} FAIL" >> ${HOME}/updates.txt
+    exit 1
 fi