loxigen-artifacts: address review comments
diff --git a/.abat-automerge b/.abat-automerge
index 90679df..772134b 100755
--- a/.abat-automerge
+++ b/.abat-automerge
@@ -5,6 +5,6 @@
 ln -sf ../../.hooks/pre-commit .git/hooks/pre-commit
 make all check-all
 
-if [[ $ARTIFACT_REPO_URL ]]; then
+if [[ ${ARTIFACT_REPO_URL-} ]]; then
     ./.build/push-artifacts.sh ${ARTIFACT_REPO_URL}
 fi
diff --git a/.build/push-artifacts.sh b/.build/push-artifacts.sh
index 2e7ec82..4d4f28e 100755
--- a/.build/push-artifacts.sh
+++ b/.build/push-artifacts.sh
@@ -1,4 +1,4 @@
-#!/bin/bash
+#!/bin/bash -eu
 
 # Push the loxigen artifacts to a dedicated git repository,
 # along with a nice commit message and a tag
@@ -9,19 +9,18 @@
     exit 1
 fi
 
-set -e
-ARTIFACT_REPO=$(mktemp -d)
+ARTIFACT_REPO=$(mktemp -d --tmpdir "push-artifacts-repo.XXXXXXX")
 
 git clone ${ARTIFACT_REPO_URL} ${ARTIFACT_REPO}
+find ${ARTIFACT_REPO} -mindepth 1 -maxdepth 1 -type d \! -name '.*' -print0 | xargs -0 rm -r
 make LOXI_OUTPUT_DIR=${ARTIFACT_REPO} clean all
 
-last_msg=$(cd $ARTIFACT_REPO && git log -1)
-last_loxi_revision=$(echo "$last_msg" | perl -n -e 'm{Loxigen HEAD commit floodlight/loxigen@([a-f0-9]+)} && print $1')
-
 loxi_head=$(git rev-parse HEAD)
 last_loxi_log=$(git log --format=oneline -1)
-git_log_file=$(mktemp)
-if [[ $last_loxi_revision ]]; then
+git_log_file=$(mktemp --tmpdir "git-log-file.XXXXXXX")
+
+if [[ -e "${ARTIFACT_REPO}/loxi-revision" ]]; then
+    last_loxi_revision=$(cat "${ARTIFACT_REPO}/loxi-revision" |  cut -d ' ' -f 1)
     echo "Last loxi revision committed: $last_loxi_revision"
     git log $last_loxi_revision..HEAD >>$git_log_file
     loxi_github_url="https://github.com/floodlight/loxigen/compare/${last_loxi_revision}...${loxi_head}"
@@ -41,8 +40,7 @@
     (
        echo "Artifacts from ${loxi_github_url}"
        echo
-       echo "Loxigen HEAD commit floodlight/loxigen@${loxi_head}"
-       echo
+       echo "Loxigen Head commit floodlight/loxigen@${loxi_head}"
        cat $git_log_file
     ) | git commit --file=-