I prefer immutable_history, but I don't want to enforce it in the project I'm working on, so in my .arcrc, I have:
```
"config" : {
"immutable_history" : "true"
}
```
The project .arcconfig has nothing in it for immutable_history, but yet my .arcrc setting is ignored.
How can I have my .arcrc config take precedence for keys that aren't included in .arcconfig?
This is using arcanist 1.3, I think but "arc version" gave me:
$ arc version
Exception
The current working directory is not part of a working copy for a supported version control system (Git, Subversion or Mercurial).
(Run with --trace for a full exception trace.)