From 2dee7cdffc67896921e4a0fcd22fd20dcd7d84df Mon Sep 17 00:00:00 2001
From: Gary Pendergast <gary@pento.net>
Date: Thu, 8 Sep 2016 23:49:30 +0000
Subject: [PATCH] Database: Fall back to `utf8` when `utf8mb4` isn't supported.

Sometimes, `DB_CHARSET` will be set to `utf8mb4`, even if the current setup doesn't support `utf8mb4`. After [38442], this can cause significant character set failures, causing the connection to fall back to `latin1`.

Instead of doing this, we now check that the connection supports `utf8mb4` before trying to use it, and fall back to `utf8` when we need to.

Fixes #37982 for trunk.

Built from https://develop.svn.wordpress.org/trunk@38580


git-svn-id: http://core.svn.wordpress.org/trunk@38523 1a063a9b-81f0-0310-95a4-ce76da25c4cd
---
 wp-includes/version.php | 2 +-
 wp-includes/wp-db.php   | 5 +++++
 2 files changed, 6 insertions(+), 1 deletion(-)

diff --git a/wp-includes/version.php b/wp-includes/version.php
index 9599271409..8a00d50eab 100644
--- a/wp-includes/version.php
+++ b/wp-includes/version.php
@@ -4,7 +4,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '4.7-alpha-38579';
+$wp_version = '4.7-alpha-38580';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.
diff --git a/wp-includes/wp-db.php b/wp-includes/wp-db.php
index f4f0826897..cc33b217a0 100644
--- a/wp-includes/wp-db.php
+++ b/wp-includes/wp-db.php
@@ -779,6 +779,11 @@ class wpdb {
 			$charset = 'utf8mb4';
 		}
 
+		if ( 'utf8mb4' === $charset && ! $this->has_cap( 'utf8mb4' ) ) {
+			$charset = 'utf8';
+			$collate = str_replace( 'utf8mb4_', 'utf8_', $collate );
+		}
+
 		if ( 'utf8mb4' === $charset ) {
 			// _general_ is outdated, so we can upgrade it to _unicode_, instead.
 			if ( ! $collate || 'utf8_general_ci' === $collate ) {