Ignoring incompatible implementation,
TerminalOpen and TermOpen events are not 1-1.
"TerminalWinOpen" was accepted as N/A in
commit c7ee6af777 .
I planned to not do this to have more test cases
after manipulating the hunks header to filter out more hunks
but Justin is eager to just mark these N/A
to bump the Vim major.minor version.
Time to move on from v8.1.x.