new file mode 100644
--- /dev/null
+++ b/testing/mozharness/README.txt
@@ -0,0 +1,1 @@
+mozharness.json is a manifest file that locks or "pins" mozharness to a repository and a revision. It is currently tracking the mozilla-b2g37_v2_2 branch rather than default.

--- a/testing/mozharness/mozharness.json
+++ b/testing/mozharness/mozharness.json
@@ -1,4 +1,4 @@
 {
     "repo": "https://hg.mozilla.org/build/mozharness",
-    "revision": "c3114f35e5ec" /* mozilla-b2g37_v2_2 branch */
+    "revision": "c3114f35e5ec"
 }