API level is disconnected from NVIM version. The API metadata holds the
current API level, and the lowest backwards-compatible level supported
by this instance.

Release 0.1.6 is the first release that reports the Nvim version and API
level.

    metadata['version'] = {
      major: 0,
      minor: 1,
      patch: 6,
      api_level: 1,
      api_compatible: 0,
      api_prerelease: false,
    }

The API level may remain unchanged across Nvim releases if the API has
not changed.

When changing the API,
    - set NVIM_API_PRERELEASE to true
    - increment NVIM_API_LEVEL (at most once per Nvim version)
    - adjust NVIM_API_LEVEL_COMPAT if backwards-compatibility was broken

api_level_0.mpack was generated from Nvim 0.1.5 with:
    nvim --api-info

The API level is disconnected from the NVIM version. The API metadata
holds the current API level, and the lowest backwards-compatible level
supported by this instance.

Release 0.1.6 will be the first release reporting the Nvim version and
API level.

    metadata['version'] = {
      major: 0,
      minor: 1,
      patch: 6,
      prerelease: true,
      api_level: 1,
      api_compatible: 0,
    }

The API level may remain unchanged across Neovim releases if the API has
not changed.

When changing the API the CMake variable NVIM_API_PRERELEASE is set to
true, and  NVIM_API_CURRENT/NVIM_API_COMPATIBILITY are incremented
accordingly.

The functional tests check the API table against fixtures of past
versions of Neovim. It compares all the functions in the old table with
the new one, it does ignore some metadata attributes that do not alter
the function signature or were removed since 0.1.5.  Currently the only
fixture is 0.mpack, generated from Neovim 0.1.5 with nvim --api-info.

Closes #5246

Problem:    Memory leak when saving for undo fails.
Solution:   Free allocated memory. (Hirohito Higashi)

https://github.com/vim/vim/commit/1e2258297bb31720bfbeb234f2dae4d1b3b04fbd

Closes #5449

A file containing the string "vim" followed by a very large number in a modeline
location will trigger an overflow in getdigits() which is called by
chk_modeline() when trying to parse the version number.

Add getdigits_safe(), which does not assert overflows, but reports them to the
caller.

vim-patch:7.4.2109

Problem:    Setting 'display' to "lastline" is a drastic change, while
            omitting it results in lots of "@" lines.
Solution:   Add "truncate" to show "@@@" for a truncated line.

https://github.com/vim/vim/commit/ad9c2a08f0509294269a2f11a59a438b944bdd5a

msg_putchar() is not updating msg_col, this causes an infinite loop. Observed
with execute('version') *nested* in another execute(), in particular this line:
    let buildtype = matchstr(execute('version'), '\v\cbuild type:?\s*[^\n\r\t ]+')
when called by :CheckHealth (see runtime/autoload/health/nvim ..
s:check_performance()).

But invoking some variation of execute('...execute("version")') is not enough to
provoke the bug, maybe it needs to be in a user function?