idhub entrypoint: make git commit footer work

docker/idhub.entrypoint.sh

@@ -18,7 +18,7 @@ END
 inject_env_vars() {
         # related https://www.kenmuse.com/blog/avoiding-dubious-ownership-in-dev-containers/
         git config --global --add safe.directory "${idhub_dir}"
-        export GIT_COMMIT="$(git log --pretty=format:'%h' -n 1)"
+        export COMMIT="commit: $(git log --pretty=format:'%h' -n 1)"
 }
 
 deployment_strategy() {