store: only add new entries to the fncache file Newly added fncache entries were not added to the in-memory cache, making it possible for 'hg convert' to cause duplicates in .hg/store/fncache. Duplicates in the fncache file are harmless, but excessive numbers of duplicates from large converted repositories may slow down execution speed considerably.

Updated test output of test-convert-baz after f2618cacb485