zsh completion: disable defaults and verbose output when completing
If ui.verbose is set to True in hgrc, commands used to provide completions
would yield bad results. For example, qpush completion would include the
patch numbers and statuses as returned by qunapplied -v, instead of just
the patch names.
Defaults are also disabled when completing to prevent similar issues when
an option is set that changes a command's output.
adding a
updating working directory
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
adding b
pushing to ../a
abort: could not lock repository ../a: Permission denied