In my testing, Pathname doesn't recognize a path with '~' as absolute. For example this Podfile dependency:

```
pod 'SWFSemanticVersion', :path => '~/dev/external/SWFSemanticVersion'
```

Results in a PBXGroup root path of:

```
<string>../../../../dev/external/SWFSemanticVersion</string>
```

Is that the expected behavior?