`hermit update` seems to (sometimes?) re-download Hermit even when it doesn't need to

```
$ hermit update
info:cashkite-conventional-commits@stable: No updated required
info:go@latest: No updated required
info:hermit@square: Fetching a new version for hermit@square
$ hermit update
info:cashkite-conventional-commits@stable: No updated required
info:go@latest: No updated required
info:hermit@square: Fetching a new version for hermit@square
```

Start by reproducing the two consecutive `hermit update` commands shown in the report and compare their output. Trace the update path that handles `hermit@square`; done means a second update does not fetch Hermit when no version has changed.

Written by the indexing model from the issue text.