largefile: use `set_possibly_dirty` instead of `normallookup`

Differential Revision: https://phab.mercurial-scm.org/D11163

hgext/largefiles/overrides.py

@@ -1785,7 +1785,9 b' def mergeupdate(orig, repo, node, branch'
         # mark all clean largefiles as dirty, just in case the update gets
         # interrupted before largefiles and lfdirstate are synchronized
         for lfile in oldclean:
-            lfdirstate.normallookup(lfile)
+            entry = lfdirstate._map.get(lfile)
+            assert not (entry.merged_removed or entry.from_p2_removed)
+            lfdirstate.set_possibly_dirty(lfile)
         lfdirstate.write()
 
         oldstandins = lfutil.getstandinsstate(repo)