Problem:    Diff and cursorcolumn highlighting don't mix.
Solution:   Fix condition for what attribute to use. (Christian Brabandt,
            closes vim/vim#7258, closes vim/vim#7260)
https://github.com/vim/vim/commit/fabc3ca896751277f18a3a68e5661179728db3ad

Problem:    Unified diff fails if actually used.
Solution:   Invoke :diffupdate in the test.  Fix the check for working external
            diff. (Ghjuvan Lacambre, Christian Brabandt, closes vim/vim#8197)
https://github.com/vim/vim/commit/ad5c178a191cf2cf37a27c2a789d7afda3879831

Problem:    Using unified diff is not tested.
Solution:   Test all cases also with unified diff. (issue vim/vim#8197)
https://github.com/vim/vim/commit/485b62710004431a16feb4eb861365d082304a08

Problem:    Diffmode completion doesn't use per-window setting.
Solution:   Check if a window is in diff mode. (Dominique Pell, closes vim/vim#5419)
https://github.com/vim/vim/commit/efcc329020ef089267f5f3994b8544eb58806311

Problem:    :diffget and :diffput don't have good completion.
Solution:   Add proper completion. (Dominique Pelle, closes vim/vim#5409)
https://github.com/vim/vim/commit/ae7dba896975051a3f0b7123faa08dac5635972d

Problem:    Multiline conceal causes display errors.
Solution:   Do not allow conceal cross over EOL. (closes vim/vim#6326, closes vim/vim#4854,
            closes vim/vim#6302)
https://github.com/vim/vim/commit/fc838d6cb0f22c77a6ee2befd034b593e1c5ea06

Port test_conceal.vim but skip tests that require screendumps.

Problem:    'wrap' option is always reset when starting diff mode.
Solution:   Add the "followwrap" item in 'diffopt'. (Rick Howe, closes vim/vim#7797)
https://github.com/vim/vim/commit/4223d43c0fb6ead1e611e4469a1680a9228b6015

Problem:    No test for diff mode with syntax highlighting.
Solution:   Add a test case.
https://github.com/vim/vim/commit/248fdb33320641804afed4bdf5dc5cddb1cf64f5

Problem:    No test for display updating without a scroll region.
Solution:   Add a test.
https://github.com/vim/vim/commit/3c8ee629745737aa231fdd123826ae021e398e49

Problem:    Line numbers below filler lines not always updated.
Solution:   Don't break out of the win_line() loop too early. (Christian
            Brabandt, closes vim/vim#6294, closes vim/vim#6138)
https://github.com/vim/vim/commit/511feec6f0a9e954f1d7353425fa51232b1a8e88