Data lost after first time restart application.

HI all,

I am facing an issue about losing data on the first time restart application with leveldb. My application is using leveldb version 1.20 and running on OpenWRT OS.

I configured to open database as below:
```c++
//database options
m_options.create_if_missing = true;

//open database
m_status = DB::Open(m_options, m_db_location , &p_db);

//write options
m_write_options.sync = true;

//read options
m_read_options.fill_cache = false;
```

The content of database directory at first time:
```
drwxr-xr-x 1 root root 140 Sep 26 10:59
drwxr-xr-x 1 root root 4.0K Sep 26 11:00 ..
-rw-rw-rw- 1 root root 4.5K Sep 26 11:02 000003.log
-rw-rw-rw- 1 root root 16 Sep 26 10:59 CURRENT
-rw-r--r-- 1 root root 0 Sep 26 10:59 LOCK
-rw-rw-rw- 1 root root 53 Sep 26 10:59 LOG
-rw-rw-rw- 1 root root 50 Sep 26 10:59 MANIFEST-000002
```

After the first time restart my application, reboot, or power cycle the machine then the database directory has changed and all my previous data is lost.
```
drwxr-xr-x 1 root root 4.0K Sep 26 11:03 .
drwxr-xr-x 1 root root 4.0K Sep 26 11:00 ..
-rw-rw-rw- 1 root root 4.5K Sep 26 11:03 000005.ldb
-rw-rw-rw- 1 root root 558 Sep 26 11:03 000006.log
-rw-rw-rw- 1 root root 16 Sep 26 11:03 CURRENT
-rw-r--r-- 1 root root 0 Sep 26 10:59 LOCK
-rw-rw-rw- 1 root root 290 Sep 26 11:03 LOG
-rw-rw-rw- 1 root root 53 Sep 26 10:59 LOG.old
-rw-rw-rw- 1 root root 131 Sep 26 11:03 MANIFEST-000004
```

This issue really confuse me because it only happen at the first time and there is no error message from leveldb.