deb: install zsh completions to /usr/share/zsh/vendor-completions...
deb: install zsh completions to /usr/share/zsh/vendor-completions
This location is used by debian (and ubuntu) to store completions provided by
other deb packages. The default fpath appears to have this before any of the
zsh-provided instances of the completions, so this should take precedence.
Differential Revision:
https://phab.mercurial-scm.org/D882