Index: wp-includes/ms-settings.php
===================================================================
--- wp-includes/ms-settings.php	(revision 35739)
+++ wp-includes/ms-settings.php	(working copy)
@@ -135,10 +135,13 @@
 		ms_not_installed( $domain, $path );
 	}
 
-	// @todo Investigate when exactly this can occur.
+	// This occurs when following the activation link sent via email in subdomain installs
 	if ( empty( $current_blog ) && wp_installing() ) {
 		$current_blog = new stdClass;
 		$current_blog->blog_id = $blog_id = 1;
+		$current_blog->domain = $domain;
+		$current_blog->path = '/';
+		$current_blog->public = 1;
 	}
 
 	// No site has been found, bail.