DifferenceEngine: Allow cache hits for empty diffs

PHP considers the empty string as falsey, so check for a string
result instead.

Bug: T216554
Change-Id: I3b7d1199acbfede8a95761c5cb1c797b9a3d64cb

diff --git a/includes/diff/DifferenceEngine.php b/includes/diff/DifferenceEngine.php
index 43bc6e4..87863a4 100644 (file)
--- a/includes/diff/DifferenceEngine.php
+++ b/includes/diff/DifferenceEngine.php
@@ -1033,7 +1033,7 @@ class DifferenceEngine extends ContextSource {
                        // Try cache
                        if ( !$this->mRefreshCache ) {
                                $difftext = $cache->get( $key );
-                               if ( $difftext ) {
+                               if ( is_string( $difftext ) ) {
                                        wfIncrStats( 'diff_cache.hit' );
                                        $difftext = $this->localiseDiff( $difftext );
                                        $difftext .= "\n<!-- diff cache key $key -->\n";