Streams: Return early from wp_is_stream() for paths that aren't streams.

Some versions of PHP appear to have a memory leak that is occasionally triggered by calling `stream_get_wrappers()`. In order to avoid calling this, we can return early from `wp_is_stream()` when `$path` doesn't contain `://`.

Props pbiron, JPry, dontstealmyfish.
Merges [43466] to the 4.9 branch.
Fixes #44532.
Built from https://develop.svn.wordpress.org/branches/4.9@43484


git-svn-id: http://core.svn.wordpress.org/branches/4.9@43311 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-includes/functions.php

@@ -5227,6 +5227,11 @@ function _device_can_upload() {
  * @return bool True if the path is a stream URL.
  */
 function wp_is_stream( $path ) {
+	if ( false === strpos( $path, '://' ) ) {
+		// $path isn't a stream
+		return false;
+	}
+
 	$wrappers    = stream_get_wrappers();
 	$wrappers    = array_map( 'preg_quote', $wrappers );
 	$wrappers_re = '(' . join( '|', $wrappers ) . ')';

wp-includes/version.php

@@ -4,7 +4,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '4.9.8-alpha-43483';
+$wp_version = '4.9.8-alpha-43484';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.