Messed-up shard recovery

[vkryzh]

We have a small CouchDB 3.1.1 database and during the application update we accidentally had two databases running simultaneously using one shared storage. One of the shards got corrupted and some help is needed to restore it. Shard is quite small (50 Mb). it may be that the corruption is only in the last appended part of the file, so as it's unimportant it may be possible to truncate the file to recover. Thank you for any suggestions or help.