`zig build --zig-lib-dir lib` in the zig repo segfaults

### Zig Version

0.11.0-dev.638+5c67f9ce7

### Steps to Reproduce and Observed Behavior

```
/zig$ zig build --zig-lib-dir lib
Segmentation fault (core dumped)
```

### Expected Behavior

```
/zig$ zig build --zig-lib-dir lib
/zig$
```