false positive results of relativePath

**Description of the issue**

I have created a [query](https://lgtm.com/query/7170632202440898188/):

```
import java
import semmle.code.java.security.RelativePaths

from Expr e, string command
where relativePath(e, command)
select e, command
```

As the query [results](https://lgtm.com/projects/g/apache/maven/snapshot/151464c4c518e8790d7c17db311ee1ff13676f9b/files/maven-artifact/src/main/java/org/apache/maven/artifact/Artifact.java?sort=name&dir=ASC&mode=heatmap#L43) of project :



Obviously, `RELEASE_VERSION` does not start with a relative path as stated in `RelativePaths.qll`.