Fix regression breaking search on prefetched rel (broken by 5e2a051)

Boy 0.08205 was a bad release, so much crap went in undetected by
any of our tests :( Maybe it's time for Devel::Cover...?

Changes

@@ -1,5 +1,9 @@
 Revision history for DBIx::Class
 
+    * Fixes
+        - Fix another embarrassing regression preventing correct refining of
+          the search criteria on a prefetched relation (broken in 0.08205)
+
 0.08208 2013-02-20 09:56 (UTC)
     * New Features / Changes
         - A bunch of nonsensically named arguments to the SQL::Translator

lib/DBIx/Class/ResultSet.pm

@@ -389,11 +389,11 @@ sub search_rs {
   my $cache;
   my %safe = (alias => 1, cache => 1);
   if ( ! List::Util::first { !$safe{$_} } keys %$call_attrs and (
-    ! defined $_[0]
+    ! defined $call_cond
       or
-    ref $_[0] eq 'HASH' && ! keys %{$_[0]}
+    ref $call_cond eq 'HASH' && ! keys %$call_cond
       or
-    ref $_[0] eq 'ARRAY' && ! @{$_[0]}
+    ref $call_cond eq 'ARRAY' && ! @$call_cond
   )) {
     $cache = $self->get_cache;
   }

t/prefetch/refined_search_on_relation.t

@@ -0,0 +1,56 @@
+use strict;
+use warnings;
+
+use Test::More;
+use lib qw(t/lib);
+use DBICTest;
+
+my $schema = DBICTest->init_schema();
+
+my $art = $schema->resultset('Artist')->find(
+  { 'me.artistid' => 1 },
+  { prefetch => 'cds', order_by => { -desc => 'cds.year' } }
+);
+
+is (
+  $art->cds->search({ year => 1999 })->next->year,
+  1999,
+  'Found expected CD with year 1999 after refined search',
+);
+
+is (
+  $art->cds->count({ year => 1999 }),
+  1,
+  'Correct refined count',
+);
+
+# this still should emit no queries:
+{
+  my $queries = 0;
+  my $orig_debug = $schema->storage->debug;
+  $schema->storage->debugcb(sub { $queries++; });
+  $schema->storage->debug(1);
+
+  my $cds = $art->cds;
+  is (
+    $cds->count,
+    3,
+    'Correct prefetched count',
+  );
+
+  my @years = qw(2001 1999 1997);
+  while (my $cd = $cds->next) {
+    is (
+      $cd->year,
+      (shift @years),
+      'Correct prefetched cd year',
+    );
+  }
+
+  $schema->storage->debug($orig_debug);
+  $schema->storage->debugcb(undef);
+
+  is ($queries, 0, 'No queries on prefetched operations');
+}
+
+done_testing;