run-tests: replace inline python handling with more native scheme Normally changes in tests are reported like this in diffs: $ cat foo - a + b Using -i mode lets us update tests when the new results are correct and/or populate tests with their output. But with the standard doctest framework, inline Python sections in tests changes instead result in a big failure report that's unhelpful. So here, we replace the doctest calls with a simple compile/eval loop.