Prevent absent version from being supplied by current version in upda…

…te check

amp.php

@@ -178,8 +178,14 @@ function amp_init() {
 	// Add actions for legacy post templates.
 	add_action( 'wp', 'amp_maybe_add_actions' );
 
-	// Broadcast plugin updates.
-	$old_version = AMP_Options_Manager::get_option( 'version', '0.0' );
+	/*
+	 * Broadcast plugin updates.
+	 * Note that AMP_Options_Manager::get_option( 'version', '0.0' ) cannot be used because
+	 * version was new option added, and in that case default would never be used for a site
+	 * upgrading from a version prior to 1.0. So this is why get_option() is currently used.
+	 */
+	$options     = get_option( AMP_Options_Manager::OPTION_NAME, array() );
+	$old_version = isset( $options['version'] ) ? $options['version'] : '0.0';
 	if ( AMP__VERSION !== $old_version ) {
 		/**
 		 * Triggers when after amp_init when the plugin version has updated.

tests/test-class-amp-theme-support.php

@@ -1318,6 +1318,7 @@ public function test_post_processor_cache_effectiveness() {
 		$args          = array( 'enable_response_caching' => true );
 		wp_using_ext_object_cache( true ); // turn on external object cache flag.
 		$this->reset_post_processor_cache_effectiveness();
+		AMP_Options_Manager::update_option( 'enable_response_caching', true );
 
 		// Test the response is not cached after exceeding the cache miss threshold.
 		for ( $num_calls = 1, $max = AMP_Theme_Support::CACHE_MISS_THRESHOLD + 2; $num_calls <= $max; $num_calls++ ) {