Investigate fork db error that was ignored on startup loading a snapshot

[heifner]

info  2024-09-24T14:38:36.367 nodeos    controller.cpp:1667           replay_block_log     ] 7744 irreversible blocks replayed
info  2024-09-24T14:38:36.367 nodeos    controller.cpp:1670           replay_block_log     ] replayed 7744 blocks in 24 seconds, 3.22407890998321101 ms/block
error 2024-09-24T14:38:36.469 nodeos    controller.cpp:1700           replay               ] Unable to open fork database, continuing without reversible blocks: {"code":3020000,"name":"fork_database_exception","message":"Fork database exception","stack":[{"context":{"level":"error","file":"fork_database.cpp","line":701,"method":"open","hostname":"","thread_name":"nodeos","timestamp":"2024-09-24T14:38:36.468"},"format":"Version 2 of fork_database (created by Spring 1.0.0) is not supported","data":{}},{"context":{"level":"warn","file":"fork_database.cpp","line":742,"method":"open","hostname":"","thread_name":"nodeos","timestamp":"2024-09-24T14:38:36.469"},"format":"","data":{"fork_db_file":"/bigata1/nodeos/data/blocks/reversible/fork_db.dat"}}]}
info  2024-09-24T14:38:36.470 nodeos    controller.cpp:1787           operator()           ] fork database has no pending blocks root 395925313 : 1799574193393ee06a5c4a39755d7d92a3eb3667d8a8ab30a090895601173d02
info  2024-09-24T14:38:36.470 nodeos    controller.cpp:1873           startup              ] Finished initialization from snapshot (snapshot load time was 1058s)
info  2024-09-24T14:38:36.473 nodeos    chain_plugin.cpp:1138         plugin_startup       ] starting chain in read/write mode
info  2024-09-24T14:38:36.473 nodeos    chain_plugin.cpp:1146         plugin_startup       ] Blockchain started; head block is #395925313
info  2024-09-24T14:38:36.473 nodeos    account_query_db.cpp:143      build_account_query_ ] Building account query DB
info  2024-09-24T14:39:24.006 nodeos    account_query_db.cpp:163      build_account_query_ ] Finished building account query DB in 47.53245100000000178
info  2024-09-24T14:39:24.428 nodeos    chain_api_plugin.cpp:117      plugin_startup       ] starting chain_api_plugin

[heifner]

Working as designed. We do validate that the fork database has to be consistent with the state. So the only time it can really be ignored like this is when starting from a snapshot. In that case seems perfectly reasonable to ignore it.