productbuild: needs to escape pkg component url references
Currently a pkg-ref is generated in Contents/distribution.dist which looks like the following if there are spaces in the main installer package name.
file:./Contents/Packages/Name With Spaces -component.pkg"
This causes the build to fail.
Escaping the spaces fixes the problem:
file:./Contents/Packages/Name%20With%20Spaces%20%20component.pkg"
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