Dolt login overwrites config with bad values

On `dolthub`, my display name is set to an empty string ("").

I then check my dolt config `dolt config --global --list`:
```
user.email me@liquidata.co
user.name iamdevdisplayname
```
I run `dolt login` and add the genned creds on `dolthub`.

I check my config again:
```
user.email me@liquidata.co
user.name
```
`user.name` is set to an empty string and now `dolt init` panics