tests: fix test-rebase-scenario-global.t

Summary: Seems like there was a typo when migrating this test, and that this should have been something related to 'G' rather than something related to '6'.

Reviewed By: quark-zju

Differential Revision: D54346444

fbshipit-source-id: dd4026e86a640688b14d636e4e8e4786eb9c321a

eden/scm/tests/test-rebase-scenario-global.t

@@ -317,7 +317,7 @@ C onto A - rebase onto an ancestor:
 
 Check rebasing public changeset
 
-  $ hg push --config phases.publish=True -q -r 6 # update phase of G
+  $ hg push --config phases.publish=True -q -r 'desc(G)' # update phase of G
   $ hg rebase -d 'desc(A)' -b 'desc(C)'
   nothing to rebase
   $ hg debugmakepublic 'desc(C)'