Problem:    Insufficient tests for tags; bug in using extra tag field when
            using an ex command to position the cursor.
Solution:   Fix the bug, add more tests. (Yegappan Lakshmanan, closes #5439)

Problem:    Complete item "user_data" can only be a string.
Solution:   Accept any type of variable. (closes #5412)

Problem:    settagstack() cannot truncate at current index.
Solution:   Add the "t" action. (Yegappan Lakshmanan, closes #5417)

Problem:    Python 3 unicode test someitmes fails.
Solution:   Make 'termencoding' empty.  Correct number of error message.

Problem:    :diffget and :diffput don't have good completion.
Solution:   Add proper completion. (Dominique Pelle, closes #5409)

Problem:    Cannot skip tests for specific MS-Windows platform.
Solution:   Add windowsversion().

Problem:    Filetype Rego not recognized.
Solution:   Add *.rego. (Matt Dunford, closes #5376)