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.
#!/bin/sh
hg init
echo a > a
hg ci -Am0
touch .hg/store/journal
echo foo > a
hg ci -Am0
hg recover