diff --git a/bin/launch-build b/bin/launch-build
index 3ca8afc43..8352f8db8 100755
--- a/bin/launch-build
+++ b/bin/launch-build
@@ -2,7 +2,6 @@
 set -euo pipefail
 
 nextstrain build --aws-batch --cpus 96 --memory 180GiB --detach \
-    --image nextstrain/base:branch-python-base \
     "$@" \
     --profile nextstrain_profiles/nextstrain \
     --set-threads tree=16
diff --git a/bin/rebuild-staging b/bin/rebuild-staging
index 1257dc79f..ebc77ee86 100755
--- a/bin/rebuild-staging
+++ b/bin/rebuild-staging
@@ -66,6 +66,22 @@ main() {
 
     echo "Notifying Slack about rebuild."
     "$bin"/notify-slack "A new staging build was submitted. Follow along in your local ncov repo with: "'```'"nextstrain build --aws-batch --attach $aws_batch_job_id ."'```'
+
+
+    echo "Launching a trial build for nextstrain/base:branch-python-base"
+
+    # Must use a config file because Snakemake's --config options seemingly
+    # don't override the profile's config files as they should.  Not sure why.
+    tee trial.yaml <<<"
+---
+S3_BUCKET: nextstrain-ncov-private/branch/new-build-base-image
+s3_staging_url: s3://nextstrain-staging/trial_
+"
+
+    "$bin"/launch-build \
+        --image nextstrain/base:branch-python-base \
+        ncov deploy_to_staging upload \
+        --configfile trial.yaml
 }
 
 # Returns 1 if both files match (have identical hashes). Else returns 0.