Only set wal after vacuum-into copies

lib/unison-sqlite/src/Unison/Sqlite/Connection.hs

@@ -104,7 +104,6 @@ openConnection name file = do
       _ -> "file:" <> file <> "?mode=ro"
   conn0 <- Sqlite.open sqliteURI `catch` rethrowAsSqliteConnectException name file
   let conn = Connection {conn = conn0, file, name}
-  execute conn [Sql.sql| PRAGMA journal_mode = wal |]
   execute conn [Sql.sql| PRAGMA foreign_keys = ON |]
   execute conn [Sql.sql| PRAGMA busy_timeout = 60000 |]
   pure conn

parser-typechecker/src/Unison/Codebase/SqliteCodebase.hs

@@ -783,3 +783,6 @@ copyCodebase src dest = liftIO $ do
   createDirectoryIfMissing True (makeCodebaseDirPath dest)
   withConnection ("copy-from:" <> src) src $ \srcConn -> do
     Sqlite.vacuumInto srcConn (makeCodebasePath dest)
+  -- We need to reset the journal mode because vacuum-into clears it.
+  withConnection ("copy-to:" <> dest) dest $ \destConn -> do
+    Sqlite.trySetJournalMode destConn Sqlite.JournalMode'WAL

parser-typechecker/src/Unison/Codebase/SqliteCodebase/Migrations.hs

@@ -192,5 +192,8 @@ backupCodebaseIfNecessary backupStrategy localOrRemote conn currentSchemaVersion
       | otherwise -> do
           backupPath <- getPOSIXTime <&> (\t -> root </> backupCodebasePath currentSchemaVersion t)
           Sqlite.vacuumInto conn backupPath
+          -- vacuum-into clears the journal mode, so we need to set it again.
+          Sqlite.withConnection "backup" backupPath \backupConn -> do
+            Sqlite.trySetJournalMode backupConn Sqlite.JournalMode'WAL
           putStrLn ("📋 I backed up your codebase to " ++ (root </> backupPath))
           putStrLn "⚠️  Please close all other ucm processes and wait for the migration to complete before interacting with your codebase."