[roll] Roll fuchsia [gigaboot] Set oneshot recovery flag when booting recovery.

Previously, hitting 'Z'/'R' to boot into recovery would pass the
zvb.current_slot flag for the current active slot, rather than always
passing 'zvb.current_slot=_r'. Fix this by setting the oneshot recovery
flag before booting if the current slot is not already R, similar to
what is done for A/B.

Test: pave nuc, hit 'R' during gigaboot to get to zedboot, check log for
      zvb.current_slot cmdline option
Original-Reviewed-on: https://fuchsia-review.googlesource.com/c/fuchsia/+/490877
Original-Revision: 8b28a7c158ed4bab34006d7d343f1fd800f863ef
GitOrigin-RevId: 1ef874d00c567afd54e70f7c59e36e5e61333264
Change-Id: I22ca8540c895757230a6ed20eeb3fb9c02cd8a6f
diff --git a/stem b/stem
index 618c70b..7a20950 100644
--- a/stem
+++ b/stem
@@ -10,7 +10,7 @@
              githooks=""
              remote="https://fuchsia.googlesource.com/fuchsia"
              gerrithost="https://fuchsia-review.googlesource.com"
-             revision="3aa6e15af87118a49cf1622817e3723ac6429bcf"/>
+             revision="8b28a7c158ed4bab34006d7d343f1fd800f863ef"/>
   </projects>
   <hooks>
     <hook name="install-environment"