install rsync

core/drupalci.yml

@@ -11,6 +11,8 @@ build:
       # Run code quality checks.
       container_command.commit-checks:
         commands:
+          # Install rsync.
+          - DEBIAN_FRONTEND=noninteractive apt-get update && apt-get install -y rsync
           - "core/scripts/dev/commit-code-check.sh --drupalci"
         halt-on-fail: true
       # run_tests task is executed several times in order of performance speeds.