If the O_* flags were non-zero, then ORing the flags would always be
true.  However, the O_* flags aren't guaranteed to be non-zero, so the
assert is invalid in the first place.

Problem:    Debugging where a delay comes from is not easy.
Solution:   Use different values when calling ui_delay().
https://github.com/vim/vim/commit/eda1da0c9a8db1400649629117e7d248c07735f7

[skip ci]

Problem:    Various small code ugliness.
Solution:   Remove pointless NULL checks. Fix function calls. Fix typos.
            (Dominique Pelle, closes vim/vim#4060)
https://github.com/vim/vim/commit/bdace838c67c1bd94e55e34270a8325933891466

Problem:    Cannot parse a date/time string.
Solution:   Add strptime(). (Stephen Wall, closes #)
https://github.com/vim/vim/commit/10455d43fef041309ce0613fa792c635dd71e3a8

N/A patches for version.c:

vim-patch:8.1.2344: Cygwin: warning for using strptime()

Problem:    Cygwin: warning for using strptime().
Solution:   Move defining _XOPEN_SOURCE and __USE_XOPEN to vim.h. (Ken Takata,
            closes vim/vim#5265)  Use 700 for _XOPEN_SOURCE for mkdtemp().
https://github.com/vim/vim/commit/6a228c6463935a73c8f21142cb7368545cfee317

before, calling vim.schedule() from inside an event would execute
the scheduled callback immediately after this event without
checking for user input in between. Break event processing
whenever user input or an interrupt is available.

Before #12937, the only way to specify the `$TERM` for a pty job was
through the `TERM` key in the job's opts dict.  This was shuttled to the
child process throug a special field on the PtyProcess object and
injected into the environment after forking.

Now that we have a proper way to specify the environment for a job, we
can simply ensure that the env dict has a proper `TERM` set and avoid
the extra shuttling of data around.

This deprecates the use of the `TERM` option, but will still honor it if
present, although at a lower priority than a `TERM` present in the env
dict.

This also fixes #13874 because we're no longer trying to overwrite
`TERM` in the env dict with the special pty `term_name`.  Doing so
raises an internal error because of the existing key which, under
certain circumstances, would cause the "hit enter" prompt.  However,
since the child process had already forked, there was no way for the
user to acknowledge the prompt and we would just hang there.