There's a closed pull request on the void-packages repository

xbps-src: consistent source style
https://github.com/void-linux/void-packages/pull/35878

Description:
On lines: 442, 458,  700, 849, and 873 - the `. FILE` style is used to source in a file. As far as I can tell, `. FILE` and `source FILE` is exactly the same. If `.` is used everywhere else, then it seems `source` should be changed to `.` for consistency unless there is a difference I'm not aware of.

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