Index: src/wp-admin/network/themes.php
===================================================================
--- src/wp-admin/network/themes.php	(revision 35773)
+++ src/wp-admin/network/themes.php	(working copy)
@@ -268,8 +268,10 @@
 
 <div class="wrap">
 <h1><?php echo esc_html( $title ); if ( current_user_can('install_themes') ) { ?> <a href="theme-install.php" class="page-title-action"><?php echo esc_html_x('Add New', 'theme'); ?></a><?php }
-if ( $s )
-	printf( '<span class="subtitle">' . __('Search results for &#8220;%s&#8221;') . '</span>', esc_html( $s ) ); ?>
+$s = trim( $s );
+if ( ! empty( $s ) ) {
+	printf( '<span class="subtitle">' . __( 'Search results for &#8220;%s&#8221;' ) . '</span>', esc_html( $s ) ); ?>
+}
 </h1>
 
 <?php
Index: src/wp-admin/plugins.php
===================================================================
--- src/wp-admin/plugins.php	(revision 35773)
+++ src/wp-admin/plugins.php	(working copy)
@@ -511,8 +511,10 @@
 if ( ( ! is_multisite() || is_network_admin() ) && current_user_can('install_plugins') ) { ?>
  <a href="<?php echo self_admin_url( 'plugin-install.php' ); ?>" class="page-title-action"><?php echo esc_html_x('Add New', 'plugin'); ?></a>
 <?php }
-if ( $s )
-	printf( '<span class="subtitle">' . __('Search results for &#8220;%s&#8221;') . '</span>', esc_html( $s ) ); ?>
+$s = trim( $s );
+if ( ! empty( $s ) ) {
+	printf( '<span class="subtitle">' . __( 'Search results for &#8220;%s&#8221;' ) . '</span>', esc_html( $s ) ); ?>
+}
 </h1>
 
 <?php
Index: src/wp-admin/users.php
===================================================================
--- src/wp-admin/users.php	(revision 35773)
+++ src/wp-admin/users.php	(working copy)
@@ -475,9 +475,10 @@
 <?php } elseif ( is_multisite() && current_user_can( 'promote_users' ) ) { ?>
 	<a href="user-new.php" class="page-title-action"><?php echo esc_html_x( 'Add Existing', 'user' ); ?></a>
 <?php }
-
-if ( $usersearch )
-	printf( '<span class="subtitle">' . __('Search results for &#8220;%s&#8221;') . '</span>', esc_html( $usersearch ) ); ?>
+$s = trim( $usersearch );
+if ( ! empty( $usersearch ) ) {
+	printf( '<span class="subtitle">' . __( 'Search results for &#8220;%s&#8221;' ) . '</span>', esc_html( $usersearch ) ); ?>
+}
 </h1>
 
 <?php $wp_list_table->views(); ?>