rebase: use obsolete.isenabled() to check for experimental.allowdivergence stable

rebase: use obsolete.isenabled() to check for experimental.allowdivergence

Now that obsolete.isenabled() can also check if divergence is allowed, let's
use it for consistency. Other experimental.evolution options are already
checked via this function.

Differential Revision: https://phab.mercurial-scm.org/D11221

--- a/hgext/rebase.py	Mon Aug 02 16:23:45 2021 +0200
+++ b/hgext/rebase.py	Wed Jul 28 13:45:41 2021 +0300
@@ -362,10 +362,7 @@
         skippedset = set(self.obsolete_with_successor_in_destination)
         skippedset.update(self.obsolete_with_successor_in_rebase_set)
         _checkobsrebase(self.repo, self.ui, obsoleteset, skippedset)
-        allowdivergence = self.ui.configbool(
-            b'experimental', b'evolution.allowdivergence'
-        )
-        if allowdivergence:
+        if obsolete.isenabled(self.repo, obsolete.allowdivergenceopt):
             self.obsolete_with_successor_in_rebase_set = set()
         else:
             for rev in self.repo.revs(
@@ -1652,7 +1649,7 @@
     successors in destination or no non-obsolete successor.
     """
     # Obsolete node with successors not in dest leads to divergence
-    divergenceok = ui.configbool(b'experimental', b'evolution.allowdivergence')
+    divergenceok = obsolete.isenabled(repo, obsolete.allowdivergenceopt)
     divergencebasecandidates = rebaseobsrevs - rebaseobsskipped
 
     if divergencebasecandidates and not divergenceok: