Issue in swift 4.2 with spaces in folder names on Linux

I found that when building a swift project with the Release config, if there are spaces in any folder names then errors are thrown during the linking process.

Linking ./.build/x86_64-unknown-linux/release/Run
clang: error: no such file or directory: '/home/ubuntu/MyApp/.build/x86_64-unknown-linux/release/App.build/Models/Contexts/PDF'
clang: error: no such file or directory: 'Contexts/AppPDFContext.swift.o' 
clang: error: no such file or directory: '/home/ubuntu/MyApp/.build/x86_64-unknown-linux/release/App.build/Models/Contexts/View' 
clang: error: no such file or directory: 'Contexts/AppViewContext.swift.o'

As you can see above, the errors are printed across multiple lines. It thinks the files are: 

• /home/ubuntu/MyApp/.build/x86_64-unknown-linux/release/App.build/Models/Contexts/PDF
• Contexts/AppPDFContext.swift.o
• /home/ubuntu/MyApp/.build/x86_64-unknown-linux/release/App.build/Models/Contexts/View
• Contexts/AppViewContext.swift.o

The folder names with spaces are "PDF Contexts" and "View Contexts"

This didn't happen on Swift 4.1.