Import as Project From a repository points to the wrong repository

Similarly to https://github.com/eclipse/gemoc-studio-modeldebugging/issues/113 and https://github.com/eclipse/gemoc-studio-execution-moccml/issues/15
the repository computed in the manifest points to an incorrect location
![image](https://user-images.githubusercontent.com/661468/59912337-260ba700-9416-11e9-8bb5-17c3943c191a.png)

