Deletions come back when insert new item

[GreyCode3]

I am writing some CLI functions and find a new situation to cause deletions back with release 4.4.1. Quite similar to #127. So, I still use example in #127:

use polodb_core::{Database, Document, bson::doc};

let db = Database::open_file("tasks.db").unwrap();
let col = db.collection::<Document>("tasks");

col.find(None)?; // The document [{ "name": "1" }, { "name": "2" },{ "name": "3" }] is returned

After that function dead. Then I read db again and delete one item:

use polodb_core::{Database, Document, bson::doc};

let db = Database::open_file("tasks.db").unwrap();
let col = db.collection::<Document>("tasks");

col.delete_one(doc! {"name": "3"})?;
col.find(None)?; // The document [{ "name": "1" }, { "name": "2" }] is returned

Now insert new data:

use polodb_core::{Database, Document, bson::doc};

let db = Database::open_file("tasks.db").unwrap();
let col = db.collection::<Document>("tasks");

col.insert_one(doc! {"name": "4"})?;
col.find(None)?; // The document [{ "name": "1" }, { "name": "2" },{ "name": "4" }] is returned

So far so good. But problem occurs if I read again with new process (means I execute function again):

use polodb_core::{Database, Document, bson::doc};

let db = Database::open_file("tasks.db").unwrap();
let col = db.collection::<Document>("tasks");

col.find(None)?; // The document [{ "name": "1" }, { "name": "2" },{ "name": "3" }] is returned !!!!

I just guess that the wal file never flush to disk. So when a new process execute and read from disk, db still use old file without updating... Maybe that's why delete and read db in same process, everything seems okay.
If I insert same data again:

use polodb_core::{Database, Document, bson::doc};

let db = Database::open_file("tasks.db").unwrap();
let col = db.collection::<Document>("tasks");

col.insert_one(doc! {"name": "4"})?;
col.find(None)?; // The document [{ "name": "1" }, { "name": "2" },{ "name": "3" },{ "name": "3" },{ "name": "4" }] is returned !!!!