Only run tests that have corresponding .save files (and unbreak dep8)
The dep8 unit test for r-cran-vegan are currently broken because it
assumes/requires that every upstream test will have a corresponding
.save
output file to compare the results against. That doesn't seem
to be the case:
https://github.com/vegandevs/vegan/tree/439efcf7839c333c0c7b015ff5c2dff54053b9ac/tests
This MR fixes the breakage by only running tests that have a .save
file associated.