When exporting from the print module - either via a printer or print to file - using the "Photo Border" setting results in Lightroom stretching images, distorting the final product. Using "Inner Stroke" does not exhibit the same issue and functions as a workaround. In the attached example I've included two screenshots. The file in this example is an image that was printed to a jpeg from Lightroom. On the left I used "Inner Stroke" during export, on the right I used "Photo Border." The guides seen were added in Photoshop for illustrative purposes. As you can see, the eye and chin guide are relatively unaffected. The side guides have not moved but the face has expanded far beyond the guides.
I'm running Lightroom CC 2015.9 on macOS Sierra.