`dapp test` errors during `git rebase`

`dapp test` doesn't work during `git rebase`, with the error

```
fatal: Not a valid object name t beef8166f2184a4bac3d02abdb944647fd7350
hevm: user error (("git",["-C","hevm.libs.4aALM","cat-file","blob","t beef8166f2184a4bac3d02abdb944647fd7350"]): exited with code 128)
```

However, `hevm dapp-test` succeeds.

Start by reproducing `dapp test` during a `git rebase` and compare it with the successful `hevm dapp-test` command. Trace the git object argument shown in the error, and consider the issue done when `dapp test` succeeds during a rebase without producing the malformed object name.

Written by the indexing model from the issue text.