watch: use detect_indexlevel for unconfigured inboxes

I favor leaving the publicinbox.<name>.indexlevel parameter
out of config files to make it easier to alter and reduce
sources of truth.  It worked well in most cases, but
public-inbox-watch also needs to detect the indexlevel.

Moving the sub to InboxWritable (from Admin) probably makes
sense since it's a per-inbox attribute and allows -watch
to reuse it.

1 files changed, 2 insertions, 0 deletions

diff --git a/lib/PublicInbox/Watch.pm b/lib/PublicInbox/Watch.pm
index 693c7181..b87abafe 100644
--- a/lib/PublicInbox/Watch.pm
+++ b/lib/PublicInbox/Watch.pm
@@ -79,6 +79,8 @@ sub new {
                 my $ibx = $_[0] = PublicInbox::InboxWritable->new($_[0]);
 
                 my $watches = $ibx->{watch} or return;
+
+                $ibx->{indexlevel} //= $ibx->detect_indexlevel;
                 $watches = PublicInbox::Config::_array($watches);
                 for my $watch (@$watches) {
                         my $uri;