diff --git a/tests/ansible/README.md b/tests/ansible/README.md
index 7eb04769..fe343125 100644
--- a/tests/ansible/README.md
+++ b/tests/ansible/README.md
@@ -8,9 +8,15 @@ It will be tidied up over time, meanwhile, the playbooks here are a useful
 demonstrator for what does and doesn't work.
 
 
+## ``run_ansible_playbook.sh``
+
+This is necessary to set some environment variables used by future tests, as
+there appears to be no better way to inject them into the top-level process
+environment before the Mitogen connection process forks.
+
 
 ## Running Everything
 
 ```
-ANSIBLE_STRATEGY=mitogen_linear ansible-playbook all.yml
+ANSIBLE_STRATEGY=mitogen_linear ./run_ansible_playbook.sh all.yml
 ```
diff --git a/tests/ansible/run_ansible_playbook.sh b/tests/ansible/run_ansible_playbook.sh
new file mode 100755
index 00000000..1df82047
--- /dev/null
+++ b/tests/ansible/run_ansible_playbook.sh
@@ -0,0 +1,7 @@
+#!/bin/bash
+# Wrap ansible-playbook, setting up some test of the test environment.
+
+# Used by delegate_to.yml to ensure "sudo -E" preserves environment.
+export I_WAS_PRESERVED=1
+
+exec ansible-playbook "$@"