Since c6a373a263, we might encounter unit templates via the
'list-units' verb. These aren't restartable (and we throw errors), so
make sure they're filtered out of the completion options.
fixes downstream bug: https://bugs.archlinux.org/task/41719
This fixes the issue noted by Zbigniew in most cases.
if a unit's name is enclosed in single quotes completion still
will not happen after the first `\'.
https://bugs.freedesktop.org/show_bug.cgi?id=78388
I think that it is better to return good results slightly more slowly,
than partial quickly. Also reading from disk seems fast enough. Even
the delay on first try with completely cold cache is acceptable.
This is just for bash, 'cause zsh was already doing this.
https://bugzilla.redhat.com/show_bug.cgi?id=790768
