Discard abandoned pipelines when a bulk command fails (#628)

PhpRedis and Relay put the connection itself into pipeline mode, so a
pipeline that is never executed leaves the connection answering every
subsequent command with the client object instead of a value. The cache
then fatals while cloning that object in add_to_internal_cache(), fatals
in array_combine() on get_multiple(), and reports false from set() and
delete() even though the writes reach Redis.

The discard() calls sat in the count mismatch branches, which are only
reachable after exec() already closed the pipeline, so they never ran
when it mattered. Move them to the catch blocks, where the pipeline is
still open.

Predis needs no cleanup here, since its pipeline is a standalone object
rather than a connection mode, but its exceptions all extend Exception
and discard() on a Predis pipeline is harmless.

Author: claude

includes/object-cache.php

@@ -1250,8 +1250,6 @@ protected function add_multiple_at_once( array $data, $group = 'default', $expir
             }, $tx->{$method}() ?: [] );
 
             if ( count( $results ) !== count( $keys ) ) {
-                $tx->discard();
-
                 return array_fill_keys( $keys, false );
             }
 
@@ -1268,6 +1266,10 @@ protected function add_multiple_at_once( array $data, $group = 'default', $expir
             $this->cache_calls++;
             $this->cache_time += $execute_time;
         } catch ( Exception $exception ) {
+            if ( isset( $tx ) ) {
+                $tx->discard();
+            }
+
             $this->handle_exception( $exception );
 
             return array_combine( $keys, array_fill( 0, count( $keys ), false ) );
@@ -1501,13 +1503,15 @@ protected function delete_multiple_at_once( array $keys, $group = 'default' ) {
             }, $tx->{$method}() ?: [] );
 
             if ( count( $results ) !== count( $keys ) ) {
-                $tx->discard();
-
                 return array_fill_keys( $keys, false );
             }
 
             $execute_time = microtime( true ) - $start_time;
         } catch ( Exception $exception ) {
+            if ( isset( $tx ) ) {
+                $tx->discard();
+            }
+
             $this->handle_exception( $exception );
 
             return array_combine( $keys, array_fill( 0, count( $keys ), false ) );
@@ -2287,8 +2291,6 @@ protected function set_multiple_at_once( array $data, $group = 'default', $expir
             }, $tx->{$method}() ?: [] );
 
             if ( count( $results ) !== count( $keys ) ) {
-                $tx->discard();
-
                 return array_fill_keys( $keys, false );
             }
 
@@ -2300,6 +2302,10 @@ protected function set_multiple_at_once( array $data, $group = 'default', $expir
                 }
             }
         } catch ( Exception $exception ) {
+            if ( isset( $tx ) ) {
+                $tx->discard();
+            }
+
             $this->handle_exception( $exception );
 
             return array_combine( $keys, array_fill( 0, count( $keys ), false ) );