[RFE] Should search history based on what is already written

When search back through history with up arrow, wrash should take what is already in the buffer into consideration as a prefix.

Last commands:
```
git status
git pull --ff upstream main
git pull
git rebase
```

If the current buffer has `git p`, hitting up once should put `git pull` in the buffer, and hitting it again should put `git pull --ff upstream` into the buffer.