Problem:    Assigning stack variable to argument confuses Coverity.
Solution:   Use a local pointer, also makes the code simpler.

Problem:    Long message test can be flaky.
Solution:   Wait for more prompt instead of ruler.

Problem:    Manually deleting test temp files.
Solution:   Add the 'D' flag to writefile().

Problem:    The do_set() function is much too long.
Solution:   Move setting of a string option to a separate function.

Problem:    CI: codecov action update available.
Solution:   Update Codecov 3.1.0 to 3.3.1. (closes #11188)

Problem:    Closure gets wrong value in for loop with two loop variables.
Solution:   Correctly compute the number of loop variables to clear.

Problem:    Line number is displayed at virtual text "above".
Solution:   Show the line number at the text line.

Problem:    The win_line() function is much too long.
Solution:   Move code to separate functions.

Problem:    Edit test is flaky when run under valgrind.
Solution:   Send some text to the terminal to trigger a redraw.

Problem:    The win_line() function is much too long.
Solution:   Move code to separate functions.