Problem: When 'rightleft' is set the line number is sometimes drawn
reversed.
Solution: Adjust how space is handled. (Christian Brabandt, closes#8389,
closes#8391)
Problem: Various inconsistencies in test files.
Solution: Add modelines where they were missing. Use Check commands instead
of silently skipping over tests. Adjust indents and comments.
(Ken Takata, closes#6695)
Problem: Tests using term_wait() can still be flaky.
Solution: Increase the wait time when rerunning a test. (James McCoy,
closes#5899) Halve the initial times to make tests run faster
when there is no rerun.
