Error on git subtrac update: index out of range error

This happened on a fresh git repo with just one commit.

Go version: `go version go1.13.8 linux/amd64`

Error message:
```
Scanning branch: refs/heads/master
Searching submodules for: refs/heads/master/audit-trigger@701646cc2c 70164
6cc2cb937c525cd939ad3329cbd4eb95e0c
panic: runtime error: index out of range [0] with length 0
```

Contents of the `.gitmodules` file:
```
───────┬──────────────────────────────────────────────────────────────────
│ File: .gitmodules
───────┼──────────────────────────────────────────────────────────────────
1 │ [submodule "audit-trigger"]
2 │ path = audit-trigger
3 │ url = https://github.com/hasura/audit-trigger
```