[roll] Roll fuchsia [sys][testing] Serve services without READABLE

Original-Bug: 101092
Run-All-Tests: true
Original-Reviewed-on: https://fuchsia-review.googlesource.com/c/fuchsia/+/876540
Original-Revision: 64646a27db97138db1071529b1618e1d9978d319
GitOrigin-RevId: 636b5c29c4db2a5740e9ca4ce03e7634ab202081
Change-Id: I4e64ad693deb7b6d01e31ac30e8a0670bd13b5d9
diff --git a/stem b/stem
index 4cff5b7..2e02353 100644
--- a/stem
+++ b/stem
@@ -11,7 +11,7 @@
              githooks="integration/git-hooks"
              remote="https://fuchsia.googlesource.com/fuchsia"
              gerrithost="https://fuchsia-review.googlesource.com"
-             revision="8bd0f8606e932fca19f77bf46fb083c4f2fd89d0"/>
+             revision="64646a27db97138db1071529b1618e1d9978d319"/>
   </projects>
   <hooks>
     <hook name="install-environment"