Posts, Post Types: Avoid a PHP warning when `get_the_content()` is called outside of the loop.

This ensures that `$pages` and other globals are only used after they have been set up in `setup_postdata()`.

Follow-up to [44941].

Props tessawatkinsllc, dontdream, spacedmonkey, squarecandy, davidbaumwald, SergeyBiryukov.
Fixes #47824. See #42814.
Built from https://develop.svn.wordpress.org/trunk@48114


git-svn-id: http://core.svn.wordpress.org/trunk@47883 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-includes/post-template.php

@@ -282,7 +282,9 @@ function get_the_content( $more_link_text = null, $strip_teaser = false, $post =
 		return '';
 	}
 
-	if ( null === $post ) {
+	// Use the globals if the $post parameter was not specified,
+	// but only after they have been set up in setup_postdata().
+	if ( null === $post && did_action( 'the_post' ) ) {
 		$elements = compact( 'page', 'more', 'preview', 'pages', 'multipage' );
 	} else {
 		$elements = generate_postdata( $_post );

wp-includes/version.php

@@ -13,7 +13,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '5.5-alpha-48113';
+$wp_version = '5.5-alpha-48114';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.