DeleteRange can not be handled correctly while memtable_insert_with_hint_prefix_extractor is enabled

I set the `memtable_insert_with_hint_prefix_extractor` with rocksdb::NewFixedPrefixTransform(length) and do some DeleteRange and then Put. We can not scan the full data if there are some DeleteRanges.

some example can reproduce this:

```
Options options;
options.memtable_insert_with_hint_prefix_extractor.reset(NewFixedPrefixTransform(3));

// do delete range
db_->DeleteRange(WriteOptions(), db_->DefaultColumnFamily(), "000", "100");

// put 001
db_->Put(WriteOptions(), "001", "");

auto* iter = db_->NewIterator(read_opts);
for (iter->SeekToFirst(); iter->Valid(); iter->Next()) {
// iterator should include "001"
}
```
Is it a known bug? And I did not see any test case for this in https://github.com/facebook/rocksdb/blob/master/db/db_range_del_test.cc