Fix broken GUID test

Author: schlessera

features/search-replace.feature

@@ -283,12 +283,13 @@ Feature: Do global search/replace
     Given a WP install
     And I run `wp option get siteurl`
     And save STDOUT as {SITEURL}
+    And I run `wp site empty --yes`
     And I run `wp post generate --count=20`
 
     When I run `wp search-replace <flags> {SITEURL} <replacement>`
     Then STDOUT should be a table containing rows:
       | Table    | Column | Replacements | Type |
-      | wp_posts | guid   | 22           | SQL  |
+      | wp_posts | guid   | 20           | SQL  |
 
     Examples:
       | replacement          | flags     |