Fixes issue with branches that start with a hash

[soulflyman]

Contribution Type: bug fix

This pull request affects the following areas:

• [ ] Front-End
• [x] Builder
• [ ] Build Plugins

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• [x] I have read and understood the contributing guidelines?
• [x] I have checked that another pull request for this purpose does not exist.
• [x] I have considered, and confirmed that this submission will be valuable to others.
• [ ] I have created or updated the relevant documentation for this change on the PHPCI Wiki.
• [ ] Do the PHPCI tests pass?

Detailed description of change: Put the branch value into quotes. So special chars like hash (#) in branch names will not effect the git clone command.