There appear to be some cases that the original metadata salvage code does not test (and may have bugs). This ticket addresses missing test cases. Any issues discovered by adding and running these new cases should get new tickets.
Some known test cases that need to be added are:
1. Missing log/journal file. Although this is tested in the python unit test test_txn19.py it is possible that the detection of that missing file in the non-salvage case does not end up returning WT_TRY_SALVAGE.
2. Zero-length WiredTiger.turtle file.
(I don't think we can recover from/salvage a zero-length WiredTiger.wt file. Salvage of that file will not find any data in the file to recover. There is nothing to salvage.)