Build status sent to shared Pipeline repo if job is aborted before main git clone is complete

## Issue

### Context
- **Gitlab plugin version**: 1.5.9
- **Job type**: Pipeline

### Problem description

Given a Pipeline job that uses a shared library, if a user aborts the job after the shared library has been cloned, but before the main project's git clone is complete, the build status will be sent to the shared library repo in GitLab, instead of the project repo.

This is because, for Pipeline jobs, the plugin figures out what repo to send build results to based on the last SCM that was cloned before the build finished. It would be good if we could differentiate between shared libraries and actual project repos in order to send the result to the right place (or not send it at all).