diff --git a/mbed-tls-restricted-pr-ci-testing.yaml b/mbed-tls-restricted-pr-ci-testing.yaml
index d3a03fb..ca833b6 100644
--- a/mbed-tls-restricted-pr-ci-testing.yaml
+++ b/mbed-tls-restricted-pr-ci-testing.yaml
@@ -48,8 +48,14 @@
         discover-pr-origin: both
         head-filter-regex: 'PR-(758|759|850|906|916|919)-.*'
         property-strategies:
-            all-branches:
-                - suppress-scm-triggering: true
+          named-branches:
+            defaults:
+            - suppress-scm-triggering: true
+            exceptions:
+              # Temporarily enable automatic scm triggering of PR-906-merge,
+              # to test the BranchIndexingCause-specific branches modified by Mbed-TLS/mbedtls-test#71
+            - exception:
+                branch-name: 'PR-906-merge'
         submodule:
           disable: false
           recursive: true