rebase: don't try to prune obsolete changeset already in the destination

With similar motivations to the previous changesets, we stop marking changeset
from pruning when it is not the command intention. In this case, we still need
to distinguish between the strip and the obsolete case.

hgext/rebase.py

@@ -1763,17 +1763,21 b' def clearrebased(ui, repo, destmap, stat'
     tonode = repo.changelog.node
     replacements = {}
     moves = {}
+    stripcleanup = not obsolete.isenabled(repo, obsolete.createmarkersopt)
     for rev, newrev in sorted(state.items()):
         if newrev >= 0 and newrev != rev:
             oldnode = tonode(rev)
             newnode = collapsedas or tonode(newrev)
             moves[oldnode] = newnode
             if not keepf:
+                succs = None
                 if rev in skipped:
-                    succs = ()
+                    if stripcleanup or not repo[rev].obsolete():
+                        succs = ()
                 else:
                     succs = (newnode,)
-                replacements[oldnode] = succs
+                if succs is not None:
+                    replacements[oldnode] = succs
     scmutil.cleanupnodes(repo, replacements, 'rebase', moves, backup=backup)
     if fm:
         hf = fm.hexfunc