By default, Vim renames a written file to a backup file suffixed with
"~" before writing the current buffer to a new file. Consequently, there
exists an intermediate state when no file exists. Should a client watch
such a file to obtain dynamic configuration info, it observes the empty
state.
Some components have builtin heuristics for such a situation. In
particular, the window layouter falls back to a predefined default
'rules' if no rules are provided as a file. So when interactively
editing window-layouter rules using Vim, it can happen that the manually
maintained rules get overwritten by the default rules.
By setting 'set nowritebackup', we can sidestep this issue by preventing
Vim from producing the bad intermediate state.
