Failure when using :override-deps in deps.edn

Reported by @stevebuik:

> I get “Manifest type not detected when finding deps..” when using relative paths for override deps in aliases. works fine outside of Cursive. Workaround is to use absolute paths but that doesn’t transfer across machines.

Example:

```
{:override-deps {nextdoc/components-portable {:local/root "../components-portable"}}
```