fixup! build(agd): rely on checksums, not timestamps

.github/actions/restore-node/action.yml

@@ -133,7 +133,7 @@ runs:
 
         if ! cmp -s <(git cat-file blob HEAD:package.json) package.json; then
           # In the event that the package.json has been modified by Endo
-          # replacements, We need to generate a yarn-installed.sum that matches
+          # replacements, we need to have a yarn-installed.sum that matches
           # the unmodified package.json.  As long as we don't explicitly `yarn
           # install` anywhere other than in this action and in the bin/agd
           # script, we should be able to reuse even Endo-overridden built caches
@@ -145,10 +145,14 @@ runs:
           stamp=$1
           shift
           find ${1+"$@"} -exec sha1sum {} \; | sort +1 > "$stamp.new" || true
-          if test ! -s "$stamp.new" -a ! -e "$stamp"; then
-            echo "No dependencies found for $stamp" 1>&2
+          if test ! -s "$stamp.new"; then
+            echo "No new dependencies found for $stamp" 1>&2
             return 0
           fi
+          if test ! -e "$stamp"; then
+            echo "No cached dependencies found for $stamp" 1>&2
+            return 1
+          fi
           diff -u "$stamp" "$stamp.new" || return 1
           return 0
         }

bin/agd

@@ -23,10 +23,14 @@ function diffsha1() {
   stamp=$1
   shift
   find ${1+"$@"} -exec sha1sum {} \; | sort +1 > "$stamp.new" || true
-  if test ! -s "$stamp.new" -a ! -e "$stamp"; then
-    echo "No dependencies found for $stamp" 1>&2
+  if test ! -s "$stamp.new"; then
+    echo "No new dependencies found for $stamp" 1>&2
     return 0
   fi
+  if test ! -e "$stamp"; then
+    echo "No cached dependencies found for $stamp" 1>&2
+    return 1
+  fi
   diff -u "$stamp" "$stamp.new" || return 1
   return 0
 }